ASP .NET application keep prompting credential - asp.net-mvc

Question

I have an ASP .NET application. I am trying to log in but it keeps asking for login even though my credential is correct and have sufficient privileges to access to the required database. I tried all solutions which I look around on the internet include changing Visual Studio project property, move NTML of Window Authentication to top, disabled Anonymous Authentication, added IIS_IUSRS, Authenticated Users, IIS user, my credential to Folder Permission. This application was not well documented, from my boss, he believes this app use Windows Authentication due to internal usage purpose. It has two parts, the first part is the app and the second is the engine. The first part app Windows Authentication is fine. I put the engine part under the same folder where the app is located in IIS. The engine is built on my dev local computer then copy to the server. My purpose to learn what the code does. I am trying to spin up the second part, is the engine, however, it seems odd to me though. I got 401.1 - Unauthorized: Access is denied due to invalid credentials if I hit Esc or Cancel the login prompt. Appreciate any help or suggestion.
FYI: The app and engine are applications stay under the website.
Website > App + Engine
IIS 7.5, Windows Server 2008 R2, VS2015, maybe ASP .NET MVC (not sure)
Here is my Web.config file for the engine
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="dotless" type="dotless.Core.configuration.DotlessConfigurationSectionHandler, dotless.Core" />
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</configSections>
<connectionStrings>
<add name="SecurityDatabase" connectionString="Data Source=TEX_ITY;Initial Catalog=TEx;Integrated Security=True;MultipleActiveResultSets=True" providerName="System.Data.SqlClient" />
</connectionStrings>
<appSettings>
<!-- ASP.NET CONFIG -->
<add key="webpages:Version" value="3.0.0.0" />
<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />
<add key="aspnet:MaxHttpCollectionKeys" value="50000" />
<!-- TEx -->
<!-- SERVICES CONFIG -->
<add key="EmailServiceUrlFormat" value="https://{0}/Services/Email/TExEmailService.svc" />
<add key="DataExecutionServiceUrlFormat" value="https://{0}/Services/DataExecution/TExDataExecutionService.svc" />
<add key="AccountProcessingServiceUrlFormat" value="https://{0}/Services/AccountProcessing/TExAccountProcessingService.svc" />
<add key="ElectronicFileTransmissionServiceUrlFormat" value="https://{0}/Services/Filing/TExElectronicFileTransmissionService.svc" />
<!-- LOGGING CONFIG -->
<add key="MasterLogLevel" value="Trace" />
<add key="MaxStoredLogCount" value="1000" />
<!-- IMPORT CONFIG -->
<add key="ImportFileEEThreshold" value="50000" />
<add key="ImportLogsStatistics" value="true" />
<add key="ThemeName" value="Forest" />
<add key="RoutesXmlFilePath" value="~/App_Data/Routes.xml" />
<add key="RotatedTextBaseUrl" value="~/TextAsImage.axd" />
<add key="FileDownloadBaseUrl" value="~/FileDownload.axd" />
<add key="CompanyImportSchema" value="~/App_Data/Schemas/CompanyImport.xsd" />
<add key="CompanyImportSchema2" value="~/App_Data/Schemas/New Schema/CompanyImport.xsd" />
<add key="TabDelimitedCompanySetupSchema" value="~/App_Data/Schemas/TabDelimitedCompanySetup.xsd" />
<add key="TabDelimitedTaxSetupSchema" value="~/App_Data/Schemas/TabDelimitedTaxSetup.xsd" />
<add key="TabDelimitedTaxDetailSchema" value="~/App_Data/Schemas/TabDelimitedTaxDetail.xsd" />
<add key="TabDelimitedCompanySetupSampleXml" value="~/App_Data/SampleXmls/CompanySetupSampleFile.xlsx" />
<add key="TabDelimitedTaxSetupSampleXml" value="~/App_Data/SampleXmls/TaxSetupSampleFile.xlsx" />
<add key="TabDelimitedTaxDetailSampleXml" value="~/App_Data/SampleXmls/TaxDetailSampleFile.xlsx" />
<add key="TransformGenerateUnMergedTaxDetails" value="~/App_Data/Transforms/GenerateUnMergedTaxDetails.xslt" />
<add key="TransformGenerateMergedTaxDetails" value="~/App_Data/Transforms/GenerateMergedTaxDetails.xslt" />
<add key="TransformGenerateMergedTaxDetailsWithXmlns" value="~/App_Data/Transforms/GenerateMergedTaxDetailsWithXmlns.xslt" />
<add key="CompanyImportSchemav1.00" value="~/App_Data/Schemas/CompanyImportv1.00.xsd" />
<add key="CompanyImportTransformv1.00to1.01" value="~/App_Data/Schemas/CompanyImportv1.00to1.01.xslt" />
<add key="CryaReportSummaryReportSchema" value="~/App_Data/Schemas/SummaryReport.xsd" />
<add key="TExCoverLetterDefaultTemplate" value="~/App_Data/TExCoverSheet.docx" />
<add key="TransformerDirPath" value="~/Uploads/TEx-Engine/Release/Transformers" />
<add key="ReportElectronicFilingSpecDirPath" value="~/Uploads/TEx-Engine/Reports/Electronic/Specs" />
<add key="ReportPaperFilingAgencyReportDirPath" value="~/Uploads/TEx-Engine/Reports/Paper/AgencyReport" />
<add key="ReportPaperFilingCustomReportDirPath" value="~/Uploads/TEx-Engine/Release/CustomReport" />
<add key="ReportPaperFilingSpecDirPath" value="~/Uploads/TEx-Engine/Reports/Paper/Specs" />
</appSettings>
<location path="." inheritInChildApplications="false">
<system.web>
<pages controlRenderingCompatibilityVersion="4.0" enableViewState="false">
<namespaces>
<add namespace="System.Web.Helpers" />
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Routing" />
<add namespace="System.Web.WebPages" />
<add namespace="Crya.Core.Extensions" />
<add namespace="Crya.Core.Linq.Expressions" />
<add namespace="Crya.Core.Utils" />
<add namespace="Crya.Core.Web.Data" />
<add namespace="Crya.Core.Web.Extensions" />
<add namespace="Crya.Core.Web.Mvc.Assets" />
<add namespace="Crya.Core.Web.Mvc.Assets.Extensions" />
<add namespace="Crya.Core.Web.Mvc.Extensions" />
<add namespace="Crya.Core.Web.Mvc.Utils" />
<add namespace="Crya.Core.Web.Mvc.Utils.Builders" />
<add namespace="TEx.Ui.Web.Extensions" />
<add namespace="TEx.Ui.Web.Models.Data" />
<add namespace="TEx.Ui.Web.Models.Data.Controls" />
<add namespace="TEx.Ui.Web.Models.Data.Domain" />
<add namespace="TEx.Ui.Web.Utils" />
<add namespace="TEx.Ui.Web.Utils.Builders" />
<add namespace="Telerik.Web.Mvc.Extensions" />
</namespaces>
<controls>
<add tagPrefix="te" assembly="TEx.Ui.Web" namespace="TEx.Ui.Web.Models" />
</controls>
</pages>
<httpHandlers>
<add verb="GET" path="TextAsImage.axd" type="Crya.Core.Web.Imaging.RotatedTextGenerator" validate="false" />
<add verb="GET" path="FileDownload.axd" type="Crya.Core.Web.Content.DownloadFileHandler" validate="false" />
<add verb="GET,HEAD" path="asset.axd" validate="false" type="Telerik.Web.Mvc.WebAssetHttpHandler, Telerik.Web.Mvc" />
<add path="*.less" verb="GET" type="dotless.Core.LessCssHttpHandler, dotless.Core" />
</httpHandlers>
<httpModules>
<add name="TExAuthentication" type="TEx.Shared.Security.TExAuthenticationModule, TEx.Shared" />
</httpModules>
<siteMap defaultProvider="CombinedSiteMapProvider">
<providers>
<add name="CombinedSiteMapProvider" type="TEx.Ui.Web.Navigation.SiteMap.TExSiteMapProvider" siteMapFile="~/Web.sitemap" areaName="" forceLowerCaseUrl="true" forceTrailingSlashUrl="true" />
<add name="EngineSiteMapProvider" type="TEx.Ui.Web.Navigation.SiteMap.TExSiteMapProvider" siteMapFile="~/Areas/Engine/Web.sitemap" areaName="Engine" forceLowerCaseUrl="true" forceTrailingSlashUrl="true" />
</providers>
</siteMap>
</system.web>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true">
<add name="TExAuthentication" type="TEx.Shared.Security.TExAuthenticationModule, TEx.Shared" />
</modules>
<handlers>
<add name="rotatedText" verb="GET" path="TextAsImage.axd" type="Crya.Core.Web.Imaging.RotatedTextGenerator" />
<add name="downloadFile" verb="GET" path="FileDownload.axd" type="Crya.Core.Web.Content.DownloadFileHandler" />
<remove name="asset" />
<add name="asset" preCondition="integratedMode" verb="GET,HEAD" path="asset.axd" type="Telerik.Web.Mvc.WebAssetHttpHandler, Telerik.Web.Mvc" />
<add name="dotless" path="*.less" verb="GET" type="dotless.Core.LessCssHttpHandler,dotless.Core" resourceType="File" preCondition="" />
</handlers>
<rewrite>
<rules>
<rule name="HTTP to HTTPS" stopProcessing="true">
<match url="(.*)" ignoreCase="true" />
<conditions logicalGrouping="MatchAll" trackAllCaptures="true">
<add input="{HTTPS}" pattern="off" />
<add input="{HTTP_HOST}" pattern="([^/:]+)(:[^/]*)?" />
</conditions>
<action type="Redirect" url="https://{C:1}/{R:0}" appendQueryString="true" />
</rule>
<rule name="Lower Case URLs" stopProcessing="true">
<match url="[A-Z]" ignoreCase="false" />
<conditions logicalGrouping="MatchAll" trackAllCaptures="false">
<add input="{URL}" pattern="WebResource.axd" negate="true" />
</conditions>
<action type="Redirect" url="{ToLower:{URL}}" />
</rule>
<rule name="Trailing Slash" stopProcessing="true">
<match url="(.*[^/])$" />
<conditions logicalGrouping="MatchAll" trackAllCaptures="false">
<add input="{REQUEST_FILENAME}" matchType="IsDirectory" ignoreCase="true" negate="true" />
<add input="{REQUEST_FILENAME}" matchType="IsFile" ignoreCase="true" negate="true" />
<add input="{URL}" pattern="WebResource.axd" negate="true" />
</conditions>
<action type="Redirect" url="{R:1}/" />
</rule>
</rules>
</rewrite>
</system.webServer>
</location>
<system.web>
<machineKey validationKey="843C54527BD577FCEEF69ABE5B4590BBDE5C035B26CB6B52920061F5221E640B4AB509E9CB22F254C37C1CADE017A34F7DD52582ECC97830F5B81FA954E8B6D0" decryptionKey="97327C072BDBA2FACFBD3526DBF6F277EE368B2DCEB76AE2E42D7538AD95CBFA" validation="SHA1" decryption="AES" />
<authentication mode="Windows">
</authentication>
<authorization>
<!-- <allow users="*" /> -->
<deny users="?" />
</authorization>
<compilation targetFramework="4.5" debug="true" batch="false" optimizeCompilations="true">
<assemblies>
<add assembly="System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<add assembly="System.Web.WebPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<add assembly="System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
<add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
</assemblies>
</compilation>
<customErrors mode="Off" />
<httpRuntime maxRequestLength="20480" />
</system.web>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="System.Web.Razor" publicKeyToken="31bf3856ad364e35" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="0.0.0.0-5.2.3.0" newVersion="5.2.3.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>
<location path="Account/LogOn">
<system.web>
<authorization>
<allow users="?" />
</authorization>
<httpModules>
<remove name="TExAuthentication" />
</httpModules>
</system.web>
<system.webServer>
<modules>
<remove name="TExAuthentication" />
</modules>
</system.webServer>
</location>
<location path="~/App_Themes">
<system.web>
<authorization>
<allow users="*" />
</authorization>
<httpModules>
<remove name="TExAuthentication" />
</httpModules>
</system.web>
<system.webServer>
<modules>
<remove name="TExAuthentication" />
</modules>
</system.webServer>
</location>
<location path="~/Content">
<system.web>
<authorization>
<allow users="*" />
</authorization>
<httpModules>
<remove name="TExAuthentication" />
</httpModules>
</system.web>
<system.webServer>
<modules>
<remove name="TExAuthentication" />
</modules>
</system.webServer>
</location>
<location path="~/Images">
<system.web>
<authorization>
<allow users="*" />
</authorization>
<httpModules>
<remove name="TExAuthentication" />
</httpModules>
</system.web>
<system.webServer>
<modules>
<remove name="TExAuthentication" />
</modules>
</system.webServer>
</location>
<location path="~/Scripts">
<system.web>
<authorization>
<allow users="*" />
</authorization>
<httpModules>
<remove name="TExAuthentication" />
</httpModules>
</system.web>
<system.webServer>
<modules>
<remove name="TExAuthentication" />
</modules>
</system.webServer>
</location>
<system.serviceModel>
<bindings>
<basicHttpBinding>
<binding name="" sendTimeout="01:00:00">
<security mode="Transport">
<transport clientCredentialType="None" />
</security>
</binding>
</basicHttpBinding>
</bindings>
<behaviors>
<serviceBehaviors>
<behavior name="">
<serviceMetadata httpGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="true" />
</behavior>
</serviceBehaviors>
</behaviors>
</system.serviceModel>
<system.webServer>
<validation validateIntegratedModeConfiguration="false" />
</system.webServer>
<dotless minifyCss="false" cache="true" web="false" />
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="v11.0" />
</parameters>
</defaultConnectionFactory>
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>
</entityFramework>
</configuration>