You will (sorry!) need to reauthorize the app with your Adobe ID if you use the app for EPUB eBooks (versus audiobooks, which aren't affected by this).
- I used the menu to view the Adobe ID authorization. The menu is in the upper-left hand corner (of the blue screen) and looks like three small, horizontal lines.
- I re-authorized the app with my Adobe ID.
- I re-downloaded the eBook I was trying to get.