Saving/Loading Game State to/from the Cloud Google Play Services

So far i got how to authenticate user, report score, achievements, show leaderboard.. I used following repo

https://github.com/playgameservices/play-games-plugin-for-unity

for referance, but still can't get how to save game and load it.

I need it to load in void Start function and write data (perhaps in void Update) to cloud after each round (without user interaction). There is only two int that need to be synced - score and coins. Would appriciate code sample with explenation