If you want to use your existing account on a new or second device, you can do the following:
1. On your old account enter the Profile Menu by clicking on your profile plate at the main menu (lower right corner).
2. At the 'Login E-Mail' field enter your e-mail address and klick on the button with the green check-mark.
3. You will receive an e-mail with a predifined password.
4. Your account is now converted to a login enabled profile
If you did not receive the e-mail with your password, you can simply set a new password by clicking on the 'Change Password' button.
5. You can now enter your e-mail address and password on any other device which will load your existing login profile.
It is very important that you set your e-mail address and password on your existing account first and only afterwards use this e-mail to login on a new device!