Overdrive app is convenient but not always very reliable. Try the following; less convenient but should work ...
See if you can borrow books on a regular computer by downloading the .acsm file from the library using a standard web browser interface.
Then use ADE to convert the book to DRM .epub, and then copy the book to the device. To copy:
If it works outside Overdrive but not within it, contact Overdrive (or get the library to).