Have you registered the CD already? Once it's registered, it is bound to the account you used. You must run Origin to play SimCity, you must run it from the account that you used to register it, and you must download the updates from the Internet in order to play the game. You will never use the CD again.
If the promo code was already registered to a different account, you won't be able to run it until you change the email address associated with the account to which it was registered.
My original answers to this thread & your other one are correct - you can run SimCity offline, after you install it through Origin. You probably have SimCity registered under a different email account. Either log in to the correct account, or follow the instructions in the link I gave you.
If you have any more problems, you might want to contact EA directly so they can walk you through the process. Happy gaming!