AZURE AD Authentication in .Net Core

I am trying to configure AZURE AD forauthentication/authorization, but it gives me 404. It does not prompt me to Login.

I have following configurations in "StartUp"

ConfigureServices

 services.AddAuthentication(AzureADDefaults.BearerAuthenticationScheme)                                                                      .AddAzureADBearer(options => Configuration.Bind("AzureAd", options));

Configure

   app.UseAuthentication();

   app.UseRouting();   

   app.UseAuthorization();