Thank you for playing and for letting me know! On phones the Begin button only works once your hero has a name (3–15 letters, no numbers or spaces), and the hint was hidden at the top of the screen, so it looked like nothing happened.
I just released a fix: the button now says "Choose a name first", tapping it takes you to the name field, and there's a 🎲 button for a random name. Could you give it another try? If you get stuck anywhere else, let me know!