I just completed 2 custom challenges worth 10k cR each, but I don’t know how to receive the cR? I made the challenge on another account, and on this one I completed it and “got first place” Now what? I want my credits… 
Either hit Turn-in or just wait until it expires. You’ll get the cR either way.
The challenge expired a few minutes ago and there is no longer a “turn-in” button…
Nevermind, I just got the credits now, after completing a game.