Check device manager under ports when you have your device unplugged probably only COM1 there.
Plug in device and refresh device manager (F5) there should now be a extra COM port.
COM4 is given as the example. 1, 2, 3, 4 and COM 1 , COM 2 etc won't work either.
So COM(no space)(number).
Also unplugging the jumper from the side (so the back light is off will give a better chance it's detected in the computer.
If that fails try install the driver from folder 1. In v1.7
Let me know how it goes.