Make sure you have connected your game to Google Play. It is the only way to save, recover and sync your progress. Your account is not saved via connecting it to Facebook.
Here's how to connect your Account to Google Play:
- Open the Play Games app on your device
- Choose Settings from the three dots menu
- Under "Your data", select "Change account for games"
- Choose the account you wish to connect to your game
Your game is now connected!
Please note that Google Play only supports one game per account. Using the same Google Play for more than one account will result in lost progress.