It's in the "Options > General Configuration > [Boards] tab > Digital board"
Note that for Linux you will also need to load libraries to support Qt5, HID and BLE. Please see the ReadMe PDF file on my web page (https://goneill.co.nz/chess.php#chessnut)
If you use the USB connection you will also need to set up some UDEV rules. I include one in the LinuxUCI.tar.gz file at the end of that web page, but you'll probably need to amend it to suit your Linux distro.
Hi, how can I pair the Chessnut Air with Lucas Chess on Linux?
I can't seem to find any "hardware boards" option in the Lucas Chess menus?
Thanks