GoogleAuthCredentials

This should be Web Client Id that you created in Google OAuth page

Desktop (JVM) only. The OAuth loopback redirect URI, e.g. http://localhost:8080/callback or http://127.0.0.1:9000/oauth2. It must be an http loopback URL (localhost/127.0.0.1) with an explicit port and match an Authorized redirect URI registered for your OAuth client in the Google Cloud console — Google's Web clients reject unregistered URIs with redirect_uri_mismatch. The desktop flow binds a local callback server to the URI's port, so the port must be free and known ahead of time. Defaults to http://localhost:8080/callback. Ignored on Android, iOS, JS and wasmJs (those platforms don't run a loopback server).