As part of the account linking flow you will be prompted to create / signin to a Rogers Media account. If you have used your email before for any Rogers Media property, including Sportsnet.ca, or had a Sportsnet+ account in the past, or used your email with another brand you may have an account for your email already.
If you know the password for that account you can use it to sign in and link your subscription to that account.
If you do not know your password you can reset it by going to: http://sportsnet.ca/forgotpassword