Can’t play with friends/family – Sudoku Friends Review

I downloaded the app on my kids’ phones hoping they can play with me. But there is no way to start a game with them. They’re playing as guests because they don’t have Facebook accounts. I’ve tried every single option and menu in this game and tried to do some research online, but there is no help. The invite via text message just opens the app, it doesn’t set you up with that opponent, which is useless. The only thing I can think of is maybe I need to level up to be able to? Or maybe Facebook is required to play with friends/family? If so, that’s a scam. I’m really disappointed.
Review by AMShirl3y on Sudoku Friends.