We have not had any issues setting up the STS login or installing the OauthExternalAuthentication module. The authentication works just fine. Also, we are not using an external provider yet; just logging in using Sitefinity credentials.
Like I stated, occasionally.. a non-Admin/non-Backend user tries to access a login-protected page. After logging in successfully, the page simply refreshes instead of redirecting to the RedirectURL in the URL parameters.
The RedirectURL is correct and like I have already stated, the User is authenticated. Again, this only happens when a non-Admin account is trying to do this. Also, I have made sure that my page permissions are correct and that the Role that this non-Admin account is under is permitted to access this page. I even set newly registered users under that custom Role upon registration, but nothing has changed.