Adafruit Trinket M0
So not an Arduino board then!You did read, undend follow the instructions from Adafruit?
Cool - but it's not an Arduino issue! This is NOT the Adafruit support forum!
The TrinketHIDCombo library is written for use with the Adafruit Gemma or Trinket. Although the Trinket M0 has a similar name to the Trinket, it is a very different board and is not compatible with that library.