Trouble downloading book from library on Nook

I downloaded a book from library, but get following message:  

Network is connected, Adobe reader has latest update. For a nano second I see title of book flashing on my computer screen (Mac) and then this message appears. Can somebody help me out here? Contacted Barnes & Nobles support, it seems that they do not know how to fix it. At least the suggestions I get do not really address this problem.