In order to keep your current progress and achievements, connect your account to your Game Center profile and use it on all your Apple devices. To connect your Game Center account to your iOS device, follow these steps:
- Tap Settings and scroll down until you find Game Center;
- Tap Apple ID;
- If you have an account, log into it. If not, then create a new Apple ID account, which can let you set up a Game Center account;
- Reopen the game and connect your Game Center in Settings > Account tab.
- Make sure you see a message saying Your progress is being saved.