Before asking for a new activation code to be sent, please check your Junk/Spam folder.
If you haven't received your access code and you still have the registration window open, on the page where you Enter the access-code there is a button called Edit email/Re-send code. Select this button and you'll be able to change your email address and/or request a new access code to be sent.
If you haven't received your activation email and you've closed the register window, you need to restart the online portal registration process.