A minor error I found
If you look at the image in the link you will see that according to this site I have 3 credits remaining however I can't purchase the book because I have no credits. Just so their is no confusion I will admit that right now I don't have any credits and my trying to purchase the book was a mistake.
edit, One more thing I noticed after I first posted, I went to buy the book because I bought some credits earlier and a little later decided to download the epub. When I went to download it though I couldn't find it in my library. I was confused so I went to purchase it again only to get the above screenshot and now the book is in my library.
Sometimes the site displays stale data , doing a force reload usually fixes that . Ideally the website would be fixed, though.
CTRL-F5 in Chrome is how you do a forced refresh there.
@guspaz Chrome often still holds its cache even with CTRL+F5. The caching is way to aggressive. To be sure nothing is cached its best to keep developer tools open (with the setting to not use cache when dev tools are open).