Make sure your progress is backed up so you never lose your account. Whether you need to reinstall the game or switch to a new device, having your account connected will allow you to recover your progress easily and avoid starting over.
To do this, connect your game to either Google Play (Android) or Game Center (iOS), depending on your device.
Here's how:
Tap your profile picture in the top-left corner of the screen
Open Settings
Scroll down to find the Sign In option
Log in with your Google Play or Game Center account
Once linked, your progress will be safely stored and can be recovered anytime by logging back in with the same credentials.