This is not the sameas Adobe Reader. Some books are available in other formats, such as ePub, which may or may not require specific software for viewing.
There may be limited users.
While many of our ebook collections offer unlimited access, some collections (Ebscohost Ebooks and Ebook Central) have limited user titles. If someone else is using a title with limited access, you may not be able to access the book at that time. Try again at another time.