The game can only recognise accounts that are activated on the device, so you must first add an account in the device settings.

Go to Settings - Accounts - Add  account.

To switch between your Google Play accounts, do the following:

    1. Open the Play Games app 
    2. Choose Settings from the three dots menu
    3. Find Change account for games

For more information, please see the Google Help article on switching between Google Play accounts.