No problem. You are free to play with your account on other iOS, Android or Amazon devices as well. What you need is a linked account. Go to the menu (on the lower right) > account> link account. Now you can enter your email address. If you wish to play on other devices, all you have to do is click on the blue button that says “Login with existing account”.
Now enter your email address and request a PIN. With this PIN you can now activate your account on other devices.
If you accidently registered a new account on another device, delete it via the settings and restart the game.