Did you give the converter 5v from the red wire on S1? Do you have the ground connected?
I know its a bummer but S2 is reserved for Lora… I wish it also could be a ttl port.
Does your computer accept the device in “Device Manager”?
Caution only plug the red wire in with the M2 usb power removed, just in case. You can input power or export power in one direction only or … pop goes the M2