Can someone show me a C# example on how to handle the call back from a Login with GitHub

[DataJuggler]

services.AddAuthentication().AddMicrosoftAccount(microsoftOptions =>
{
    microsoftOptions.ClientId = "xx";
    microsoftOptions.ClientSecret = "xx";
    microsoftOptions.CallbackPath = "/Index/MicrosoftAuth";
}).AddOAuth("GitHub", options =>
{
    
    options.ClientId = "xx";
    options.ClientSecret = "xx";
    options.AuthorizationEndpoint = "https://github.com/login/oauth/authorize";
    options.TokenEndpoint = "https://github.com/login/oauth/access_token";
    options.CallbackPath = "/Index/GitHubCallback";
});;

Using this I was able to get the button to come up, although I had to rename Oauth to Git Hub during ExternalLogins, and when clicked GitHub asked me to authorize my app, but I think I am not using Octokit here? Is that correct? I did add the Nuget package, but then got stuck.

How do I show a Login with Git Hub button with Octokit is a related question. I am in a Blazor server app, and added a bunch of Microsoft Identity stuff.

Thanks, I have googled for days and not found a good C# example for this, which surprises me.

This did add a user in AspNetUsers, but on the next login I don't know where to check if the user already exists because it says User already registered.

Thanks for any guidance.