During the sign up or device activation process, you will be able to view your Apple TV activation code once you select "Start Your Free Trial" or "Already a subscriber? Sign up":
  1. After selecting one of those options, you'll be presented with the activation code.
  2. Visit cbs.com/appletv on your computer or mobile device, enter your activation code, and select "Submit". 
  3. Sign up or sign in to a CBS.com account.
  4. You will see a confirmation screen, your Apple TV screen will refresh, and you can start watching CBS All Access!