Add silent Google Play Sign in into my app -- 2

I would like you to add Google Play Games Services onto my app. namely silent sign in into my app. using android studio project . After Login I would like the Users Level to be shown using a script call in javascript. And An Achievement which i have already made, stating that the user has successfully started game. The Game was made using Rpg Mv Engine if that helps. It already has Google ads in the Android Studio Project.