Transferring ebook to Nook

I had to reinstall my operating system on my MacBook computer.  I have checked out an ebook from the library and it shows up in my Adobe Digital Editions page.  When I plug in my Nook, it also shows up.  When I try to drag the book to the Nook, I get an error saying the "CE_COPY_NOT_ALLOWED - No permission to copy the book.

On the new system I have downloaded and installed Adobe Digital Editions and OverDrive (from the library).

On my OLD system, this worked and I just dragged the checked out books onto the Nook and they copied to the Nook.

Now, I don't know what to do ? ?