Sorry for the delayed response. I am just getting back to this again.
The IDE version I am using is 1.8.13.
In the Windows Device Manager, when the CP2102 is plugged in it reads “Silicon Labs CP210x USB to UART Bridge (COM10)” under the Ports (COM & LPT) currently.
So, today everything seems to work. The following is info that may or may not be helpful as I don’t really know why it wasn’t working before. There may have been a glitch with the DC-DC converter, or just as likely, a coincidence. I connected through the FTDI socket and was getting a getting a power surge warning on the usb port prior to even turning on the Mayfly. This was new. I had not yet connected a 12V power source, though the DC-DC converter was plugged into the Mayfly’s usbc port (and had been without a power source for a few weeks). I Disconnected the DC-DC converter from the system and the error went away. I was also then able to upload through the FTDI socket. Plugging the converter back in, adding in the 12V power source, the FTDI socket still works and the serial monitor displays the sensor data. So, I guess I am set for now.
Thank you again for your help!