I’ll order a USB/parallel adapter to see if the code generally works. But let’s also try and find out about your system.
Can you tell us what the device is (brand and model if possible)?
Possibly PsychoPy isn’t finding the right address for it. You can find this out in the mac terminal window by entering these command before and after inserting the usb cable and seeing which addresses change (when you plug in the usb cable a new address should appear):
ls /dev/tty*
ls /dev/cu*