This is almost definitely not a problem with the instrument (although we're happy to take a look). The right driver depends on whether your OS is 32 bits or 64 bits, which depends on your computer. If the computer is relatively new, it's almost definitely 64 bit. In windows 10, go to SETTINGS > SYSTEM > ABOUT to get a readout to be sure.
All of that said, a quick test seems to show that just plugging the cable into windows 10 MAY (I'll need to check this next week against an actual EFIS yield the right drivers from what windows has built-in. So what you might try doing is going to device manager with the adapter plugged in, then finding the USB/Serial converter under ports (it will probably say prolific something or other), then go to properties, then the driver tab, then uninstall the driver entirely. Then unplug the cable, reboot, plug it back in, and check in device manager that there aren't any errors.