I have an iPhone and set mine up long ago, but I believe there were instructions in the MDE app.
Click the 3 lines in lower right and scroll down to Account, then tap Set Up MagicMobile Entry. I think it will walk you through the process. Good luck!
I use Google wallet. When I open my WDW card, don't go to show code. Go to the 3 dots in the top right corner. That's the only place where my DVC-Y shows up on my "card".