Love this, but it only works on my iPad, not on my iPhone – Math Splat Review

My kids love this app, and I love the new custom mode features that really help my kids drill certain facts. However, whenever I try to use it on my iPhone 6 Plus, I can't get past the setup screens to the actual game. Is there a version that works on the iPhone? Is anyone else having the same problem? (I already deleted and reinstalled the app a few times...) Thanks :)
Review by Cacooning on Math Splat.