Hi there!
I using Unity Cloud Save in my game,
and when I open Cloud Save backend service, and go to “find players” so I found a lots of player names, But I still don’t know how exactly much of players?
This is should be necessary feature, because we can calculate a cost of this service!
This is how:
Pages 1-10 means 10 pages times 10 players per page so the number of players is 91-100. If you want the precise number go to the last page and count. 
Other than that check the Admin API it might just have that sort of functionality.
Still finishing up that calculator … will let you know when I publish it.
