I set up everything according to what little information that came with the 300. I don't even show a Prolific anything or COMM 3 or any COMM in my device manager. I must really need some powerful help.
I have no idea what I have done wrong, or did not do.
You at least can see some changes in the device manager if you connect the GMC-300. IF not, then you need to confirm you have a good USB port, Good USB cable too. Try it on another computer to confirm.