The email address is your username. So insert the right one to get a confirmation email. Without a confirmation email you will not be able to complete your registration.
After registering, you need to look for a confirmation email in the mailbox. If you can't find it, look also in the spam or junk email folder. You must use the link in confirmation mail to successfully register.
After the first successful login, you will be directed to the CS4 registration page where you will enter the rest of registration data.