My apologies; I did not realize that’s what you meant when you said you said it shows up as a generic serial port. The name showing up as something like “USB Serial Device” can happen when you connect the controller before installing our drivers, but it should not prevent you from using the port. If you want to fix it, you can follow the instructions under the “USB troubleshooting for Windows” heading in the “Installing Windows drivers and software” section of the SMC G2 user’s guide, which reads:
If the drivers for the Simple Motor Controller’s USB serial ports are working, you should see an entry in the “Ports (COM & LPT)” category named something like “Pololu High-Power Simple Motor Controller G2 18v15 Command Port”. The serial port might be named “USB Serial Device” instead if you are using Windows 10 or later and you plugged the controller into your computer before installing our drivers for it. The generic name in the Device Manager will not prevent you from using the port, but we recommend fixing the name by right-clicking on each “USB Serial Device” entry, selecting “Update Driver Software…”, and then selecting “Search automatically for updated driver software”. Windows should find the drivers you already installed, which contain the correct name for the port.
Note that the drivers and software for the G2 version are different from the original SMC, so you should double check that you installed the correct version.
Have you tried opening the Simple Motor Control Center G2 and expanding the “Connect to:” drop-down menu to see if it is showing up?