Ok, first of all go and read following topic to get understanding about each part of your system and how it’s working together and where each part of it is located.
If you read it then now you should understand that MainSail is just last peace of puzzle. And we should concentrate on the “host”.
Judging by path names - most probably you have Raspbery PI there and most probably it’s task to run Mainsail + Moonraker + klipper “host” + Linux Virtual MCU(optionaly).
If I did describe your system right - then you need to use SSH and login to your raspbery, then go to that place where “printer.cfg” should be and check if it’s there.