jasper, it does not look like you ran the command in the instructions. I’m not sure how you got the output you just posted.
Open the terminal app. It is in /Applications/Utilities/Terminal.app
Change to the directory you have your dfu-programmer in by typing this at the command prompt:
cd /Users/jasperkomassa1/Desktop/synthino\ xm/dfu-programmer-0.6.2
Run the dfu-programmer command as described above:
./dfu-programmer atxmega128a4u flash --erase-first synthino_xm_v1.1.hex
…where “synthinog_xm_v1.1.hex” is the name of the .hex file you want to load. It is assumed that you saved this file in the same folder as the dfu-programmer utility.