Squawk requires your ProTracker files to be converted into Squawk melodies.
Melodies come in two flavors:
As data you put in your sketch to download with your code.
sketches/Squawk_player
As a file on an SD card connected to your Arduino.
sketches/SquawkSD_player
Both formats can be generated by converter in the convert/ directory.
That's what I assumed this said at least :o
Now I just have to get my head wrapped around how I work things in OpenMPT, as it seems that's where things go wrong.
Thanks so much for all the help!