Symptoms

The connected scanner does not appear as available for scanning in ABBYY FineReader PDF for Mac.

Cause

FineReader PDF for Mac is compatible with scanners supported by the Image Capture application (ICA) (a default program for scanning on Mac). See also: Specifications for FineReader PDF for Mac®.

The situation may appear because of the incorrect operation of the scanner's driver (or if the appropriate ICA driver for the scanner has not been installed).

Resolution

1. Make sure that the scanner is connected to your Mac and turned on (the scanner should be visible in Settings > Printers and Scanners). 
2. Go to Image Capture, check if the device is displayed as available. Check if you can scan in the app.
3. If the scanner does not appear or you cannot scan a file in Image Capture, try to install the correct scanner driver:
   1) Download ICA Scanner Driver from the scanner vendor's website. Run the downloaded .dmg file;
   2) Run Macintosh HD > Library > Image Capture > Devices > [Scanner model];
   3) After that, the Image Capture App will recognize the scanner and work with it.
   4) Restart your Mac to be able to work with the scanner in FineReader For Mac.