Question for Android users who've tried the Mainchan App?

So I got a link today from the developer to try it (thank you seriously!)

But when I go to open it I get the option to either download the public version or directly from Google play.

When I choose either of those options, the play store opens but on a blank Google play screen not displaying the app.

Am I doing something wrong? How'd you get it to work so you can try the app?

Thanks in advance!