Authorization of Computer Error "E_ADEPT_REQUEST_EXPIRED"

Hello Everyone!

I purchase a textbook through my University's bookstore and followed the instructions for downloading Digital Editions to be able to access the book. When I got to the point of "Authorizing my Computer", I entered in my login details (I know these are correct), and I get the "activation server error" code "E_ADEPT_REQUEST_ EXPIRED". It will not let me proceed to my textbook without this being completed. I have seen other threads that suggest that my computer's time is incorrect, but it's matched to my timezone and hasn't been touched in months. Also, I purchased this textbook TODAY! How can it be expired already? 

Please help!