I had the same problem. I even set up a second Apple ID and was able to submit an application to upload free books. the account was created, but I never received an email response from Apple instructing me as to how to activate the Free Books Account. Without account activation, I can't access the iTunes Producer software to upload my book.
Apple's iBooks Author customer support isn't very helpful - no telephone numbers to get a live body to discuss the problem - and Apple's email responses have not solved my issue either. I've been an Apple loyalist for three decades, but the whole iTunes Connect book publishing experience is really trying my patience. It's extremely frustrating to have spent the time and effort to create a multi-touch book and then have to jump through so many hoops to get the thing published. I like the flexibility and creative option offered by iBooks Author, but the whole publishing experience is making me seriously consider Kindle publishing.