How to implement Google Nearby API into a game?

I want to implement Google Nearby API into my game.
I found this Inizia a utilizzare i servizi per i giochi di Play per C++  |  Play Games Services  |  Google for Developers , but i don’t know how to begin with.
Can someone help me?

Its already available as a unity plugin through the official play game services which you can find here:
https://github.com/playgameservices/play-games-plugin-for-unity/blob/master/NEARBY.md

@Skjalg thank you for your reply. I will try do it first