They don't connect directly, you need ASCOM acting as a messaging hub between your PMC8 and (say) CdC.
Command ASCOM w/PMC8 driver to connect to the PMC8 first, via the button on the POTH panel. You should then see the little POTH panel lit up and connected to the scope. Don't be surprised if you have to command POTH to connect two or three times, before it works - that's my experience anyway (wired connection).
This all assumes that your physical connection to the PMC8 (wifi or cable) is working as it should, and that the parameters in the driver are correctly set up.
Then tell CdC to connect to the POTH hub, (NOT the PMC8). Should work fine.
Hope this helps...