What can I do with this message: unable to download, Error getting license, License Sever Communication Problem

I am trying to download a library book (Epub ebook) into my Mac laptop. I have updated my Adobe Edition to 4.0. I keep getting this message

Unable to download, error getting License, License server communication Problem E_ACT_NOT_READY

I have gotten in touch with the library. They advised me to do the following:

Mac OS

Open Adobe Digital ! Editions.

Press Command+Shift+D to deauthorize Adobe Digital Editions.

Select Erase Authorization.

Click OK and Quit Adobe Digital Editions.

Navigate to /Users//Library/Application Support/Adobe/Digital Editions and drag the activation.dat file to the trash.

I am stuck on  Erase Authorization.  After I choose erase authorization another message pops up: Unable to  Erase Authorization. Please try again after some time. I tried all day in fact I even went to the Apple Store where a staff member was also unable to get any further!!