Owin OpenId Callback url - asp.net-mvc

Question

I'm working in implementing OpenId in a .NET MVC application.
I have used: https://learn.microsoft.com/en-us/azure/active-directory/develop/quickstart-v1-aspnet-webapp
as a starting guide. It is working, but i have 1 question regarding RedirectUri and CallbackPath.
If i only use RedirectUri, the callback page in my application gets a 302 redirection.
If i use CallbackPath the callback page is actually hit.
It is not really clear from the example what is going on? This is from MS:
"An optional constrained path on which to process the authentication callback. If not provided and RedirectUri is available, this value will be generated from RedirectUri."
I'm using [Authorize] attribute on my controllers.
Code Startup.cs:
public void Configuration(IAppBuilder app)
{
app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType);
app.UseCookieAuthentication(new CookieAuthenticationOptions());
var openIdOptions = new OpenIdConnectAuthenticationOptions
{
// Sets the ClientId, authority, RedirectUri as obtained from web.config
ClientId = ApplicationIdentifier,
Authority = FederationGateway,
RedirectUri = RedirectUrl,
ClientSecret = AppToken,
AuthenticationMode = AuthenticationMode.Active,
//CallbackPath = new PathString("/callback/"),
// PostLogoutRedirectUri is the page that users will be redirected to after sign-out. In this case, it is using the home page
PostLogoutRedirectUri = "~/home/loggedout/",
//Scope is the requested scope: OpenIdConnectScopes.OpenIdProfileis equivalent to the string 'openid profile': in the consent screen, this will result in 'Sign you in and read your profile'
Scope = OpenIdConnectScope.OpenIdProfile,
// ResponseType is set to request the id_token - which contains basic information about the signed-in user
////ResponseType = OpenIdConnectResponseType.IdToken,
ResponseType = OpenIdConnectResponseType.IdTokenToken,
// ValidateIssuer set to false to allow work accounts from any organization to sign in to your application
// To only allow users from a single organizations, set ValidateIssuer to true and 'tenant' setting in web.config to the tenant name or Id (example: contoso.onmicrosoft.com)
// To allow users from only a list of specific organizations, set ValidateIssuer to true and use ValidIssuers parameter
TokenValidationParameters = new TokenValidationParameters()
{
ValidateIssuer = false
},
// OpenIdConnectAuthenticationNotifications configures OWIN to send notification of failed authentications to OnAuthenticationFailed method
Notifications = new OpenIdConnectAuthenticationNotifications
{
AuthenticationFailed = OnAuthenticationFailed,
SecurityTokenValidated = OnSecurityTokenValidated
}
};
app.UseOpenIdConnectAuthentication(openIdOptions);
AntiForgeryConfig.UniqueClaimTypeIdentifier = IdentityNameIdentifier;
}