You can follow these steps to link your account:
1. After downloading the game, you can select ‘Sign in with Google’ on the login interface to log in and link the account. After the account is linked, you can log in to your game account on different devices.
2. If you chose New Game to login with a Guest account, after you've finished the Deck Edit tutorial you will be prompted to connect to a Google account.  If you decide not to connect accounts at this point, you can tap on the gear icon at the top left corner of the homepage in the game, then tap ‘Sign in with Google' whenever you are ready.