If you're playing in the mobile app and wish to link your game account to an email address, you'll need to sign in to your game account first, regardless of your login method.
If you use a guest account, select the "Guest login" option.
Open the Menu.
Go to the Account section, then select "Account linking."
Tap Email.
Enter and confirm your email address.
Accept the Terms of Service and other required agreements.
Choose whether to opt in to marketing communications (optional).
After tapping OK, you'll receive an email with a PIN code. Enter this code to complete the verification.
Once you've entered the correct PIN code, your email address will be successfully linked to your account.
Note that once you have chosen to link your account to an email address, this login method cannot be removed. Your account must remain linked to an email address. However, you can change the email address associated with your account by following the instructions provided in this article.