ChessUp to ChessUp play works as a direct challenge to a specific player. We do not have a random pool to connect with.
If the app suggests that, I apologize we will need to fix that.
We do have a thread with a list of other players to friend - and @Criptix runs a club on Chess.com for the chessup 2 users.
Lichess Lichess Users - Share Username to Add Friends
Chess.com Chess.com User Names - Share if you would like to play ChessUp vs ChessUp