BEFORE you can start converting, DNxHDconverter expects the ffmpeg & ffprobe executables in the standard unix path usr/local/bin. In the app Settings, you can specify any other path to the executables. They are not bundled with the app because of licensing reasons. If you don’t have the executables, you can download them here: https://evermeet.cx/ffmpeg/
Note: The first time ffmpeg & ffprobe are launched on your Mac, a system message will appear saying “ffmpeg can’t be opened because it is from an unidentified developer”. You will need to open the system Settings, go to “Privacy and Security” tab and authorize the unsigned executables to open on your Mac. You may have to click the “unlock” button and enter your password to be able to click “Open Anyway”.