How to connect with google services in unity?

Question

Unity

You need to link the unity game with google services. I do it through play-games-plugin-for-unity. How to fill in "Google Play Games - Android Configuration". I only have cloud saves in the game. The game is published as "for internal testing". In the description, you need to go to "Achievements" and get resources - but I don't have Achievements (when I go there, there is no such table with achievements).

Where can I get Resources?
"Constants class name" - Is this the name of the class where I initialize the services (I have a GooglePlayManager) ?
"Directory to save constant" - where is this class file located (I have "Assets/Resources") ?

Another reason is Game Services> Information about the game from All Applications> My Application> Application Page> Application Description - name, description, full description, icons, etc. why do they need to be duplicated here and there?