Very odd.. <.< It could be a device side issue possibly. (Hardest part about mobile support/specs) I don't know if you have another phone device or tablet you can try downloading it on to test if it works. We'll try to look into things on our side with the engine, but sadly with mobile. There's a lot more variables going on with it works for one person without any issue, but someone else's device can't launch it, buttons not working, etc.
Regardless, thank you for bringing this to our attention. I can't promise we'll be able to fix this, as there's a number of factors at play and our primary development focus for now is more on pc/mac versions working as intended. (We'll still try putting time aside though if there's anything we can do on our end, sorry for the troubles! >.< )