+1 on getting DMR amateur equipment from Bridgecomm systems, due to their customer support and "university" tutorial videos. My only grips is that after programming hundreds of Motorola XPR6xxx/7xxxe radios, I now get hounded for only completing 4% of the "university" tutorials. The Anytone AT-D878UV is a great radio for amateur use, the hardware is well made, but as mentioned the firmware and CPS is still a little flakey. Getting the radio to work in the 220 MHz range is not really worth it as well. Stick with VHF/UHF and the software works much better with the hardware.
Windows 7 and Windows 10 had the com port come right up after driver installation, as COM7. As other have stated, let it load itself from the Internet if possible. The driver is Firmware specific as well. So, you may have to search by the firmware in your radio, for the appropriate driver for your Windows version.