Matt,
Try this, and tell us at what stage you run into problems:
- With RadarBox plugged in via the USB cable, open up the device manager and look at your devices, including the "Unknown Device"
- Unplug the RB USB cable, does the Unknown Device disappear, or does another USB device in the list disappear - we need to make sure that you are actually trying to install the driver to RB, not some other random device.
Right, can you get this far?