The registration email can get caught in spam filters or just take a minute. If you never got it, you can't finish setting up the Canon Inkjet Cloud Printing Center.
First, check your spam or junk mail folder for an email from Canon with a URL link. If it's there, click the link. You'll need to agree to the license and privacy statements, then register a password.
If that didn't work: The email might have been sent to the wrong address. Double-check the email you entered during setup. If it's wrong, you'll need to start the registration process over.
Also, the service requires an Administrator. That's usually the first person who registers. If you're trying to add users (like family members), the Administrator has to do it from the 'Manage users' screen inside the Cloud Printing Center. They select 'Add user' and follow the prompts.
Heads up: You can't delete yourself as a user from the 'Manage users' screen. To do that, you have to cancel your membership from the 'My account' screen.