Anybody can read the books on the site. However, in order to have your students create talking books using their “easy as pie” (and free) process, you need to register and have to have a code. They’re rightfully concerned about publishing the code because of spammers.
Gary Bishop from the site, though, is happy to provide it to teachers. Just write him at email@example.com and he’ll send it to you.
Sorry I neglected to include this information in my original post.