When you do, if you use the Mac, you can also provide them with
http://raspberrypi.stackexchange.com...ard-from-a-mac
It's not specific to this, but it should get a computer savy person to a point that they can do this for you. This is just for creating the clockwork SD card from the clockwork.img file. Which again is the hardest part. After this you just plug the card back in to your Mac and drag and drop the script from the glow worm page I linked to originally.
Then you can follow the instructions on the glow worm page and you'll be set.
Hope you can get this going, BN seems to really want to clamp down on allowing customers to download their purchased books.
Another possibility occurred to me, if you have access to a computer running Windows 10 then you can install the Nook app through the Microsoft store (it's free). This one still should work without an issue. You'll need to enable hidden folders to find the ebooks it downloads. This is an easy thing to do.
However even if you do have access to a Windows 10 computer I would still suggest getting the micro SD card trick up and running as there is no way of knowing if or when BN will disable access for the Nook App for Win 10.