Set up a Google sign-in with Unity Authentication (UGS) Request failed: 401

Hello! The documentation for Google sign-in states that I should use the Google Play Games plugin for Unity v10.14.

Will this work on iOS and Android?
Can I NOT use the Google Play Games plugin for Unity v10.14?

I have a very convenient plugin called Simple Google Sign-In from the asset store, which allows me to obtain a Google access token. But when I call the method:

await AuthenticationService.Instance.SignInWithGoogleAsync(idToken);

I get an error:

[Authentication]: Request failed: 401, {“detail”:“validation failed”,“details”:,“status”:401,“title”:“PERMISSION_DENIED”}

Could the problem be with the Client ID?

I created a Type Web application and set the ID in gaming services - player authentication, but it didn’t solve the problem.