Not at all. Simply use the FeedBlitz form on the site you want to subscribe to or go to www.feedblitz.com/f?Track to set up your subscription to any site. You don’t have to log in or register first; the subscirption process takes care of everything for you.
If you are using a form on a third party web site and it takes you to the account registration page at FeedBlitz then the form on the site is broken. Please let the folks at FeedBlitz technical support know of the problem and they will try to reach teh site owner to correct the problem.