It's your device. The game doesn't seem to support older devices now. I use iPhone 5c and I have 0 problems. Maybe update your device and you will thank yourself for doing it. Ask anyone who's played on a older iPad or iPhone 4/4s, when they get a new phone the game is great again.
We do because scammers fish here and I don't want players here getting scammed. He's better off buying from an established player. That's my advice to anyone coming to this thread.
Don't deal with people who have 10 posts. Find someone that is credible and has been here for a long time and has a positive track record. I'd pass on anyone new here selling anything.