Apple Sign-In on iOS 13+ uses ASAuthorizationAppleIDProvider, which handles everything natively. You don’t need to pass an authUrl because the native APIs already manage the authorization flow. Apple authenticates the user by Apple ID and it returns an IdToke, name and email (last 2 might not always come).

Might want to check the configuration of Apple’s OpenID Connect implementation: https://account.apple.com/.well-known/openid-configuration.

Hope this helps.