Cannot get ADE to recognize my new device

If that is a tablet device it may not be recognized by ADE.

You must load an Adobe DRM compatible app on the tablet (such as Bluefire or Aldiko) and register that with the same ID you use for ADE.

Then use file manager (Windows Explorer. Mac Finder) on the computer with the Nook plugged in to copy books to the Nook, which should show up as a mounted drive.