>where is the link for the registration, the only way I can get to the API is through their registration where I have to enter a creditcard number.

I was on phone when the technical support guided me to the proper link. To be sure, you may call 800-810-9073 or email websupport@fedex.com to indicate that you want to register by the online application form on their Web site for the Fedex XML interface and they should be able to help you.