Microsoft Graph API 403 error Failed to get license - microsoft-graph-api

Question

As part of an automated process to create teams and channels need to provision the email.
Provisioning the email is a delegated operation whereas the initial teams and channel creation is 'application' thus requires no user involvement.
Have created an 'automation' AD user with minimal system access and created the associtated Azure 'application' with the appropriate Graph permissions - and this works no problem however for the 'automation' user getting:
Failed to get license information for the user. Ensure user has a valid Office365 license assigned to them
The message is self explanatory - so the question is, is it possible to perform basic Teams graphAPI operations such as provisioning email addresses and maybe sending messages without an O365 license - something like a Guest account?
The following code works for accounts with o365 licenses:
var UserName = "automationbotuser#somewhere.com";
var Password= "2w234234##$$%^^&^&*(erfwerwepassword";
var TenantId= "azuretentant";
var Client_Id= "azureappclientid";
var teamId = "b2342300d12-923e-46sdfsd5e-ae98-9132424db2250bc";
var projectChannel = "19:e5fe8e53ee6brwerwf8b3323438ab59913ef42#thread.tacv2";
// using Azure.Identity;
var options = new TokenCredentialOptions
{
AuthorityHost = AzureAuthorityHosts.AzurePublicCloud
};
//create credentials
var userNamePasswordCredential = new UsernamePasswordCredential(
UserName, Password, TenantId, Client_Id, options);
var graphClient = new GraphServiceClient(userNamePasswordCredential);
//do a basic call to verify we can see something..
var user = await graphClient.Me.Request().GetAsync();
//provision the email address
await graphClient.Teams[$"{teamId}"].Channels[$"{projectChannel}"].ProvisionEmail()
.Request().PostAsync();
//remove it
await graphClient.Teams[$"{teamId}"].Channels[$"{projectChannel}"].RemoveEmail()
.Request().PostAsync();