Use platform-specific sign-in
A platform sign-in creates a new player for the game session with input from the player (for example, sign-in credentials like a username and password) and is a sure way to link a player to a platform account. This is done by using external ID providers to enable platform account sign-ins in your game, such as Google Play Games, Apple, Facebook, and Steam.
Before using external ID providers to enable platform account sign-ins within your game, you have the option to implement anonymous login by calling the LinkWith* APIs when upgrading the anonymous account.
If the player signs in with a platform account, the SignInWith* APIs are called to authenticate the players or create a new player.
See the platform-specific sign-in guides for these supported external ID providers: