Mach doesn’t play nice with other software - it is the controller, and just sends step and direction signals to whatever is plugged into it. There are some boards, like SmoothStepper, that do a bit more of their own work, but Mach still manages all the stuff that would normally be handled by a controller. You can export GCode from LightBurn and load it into Mach, but Mach won’t let other software drive it directly as far as I know.