Did you buy this board? https://www.buildyourcnc.com/item/el...ach3-USB-Board
If do, it won't work with Mach4. You need a motion controller that supports Mach4, and has a Mach4 plugin.
PMDX sells 5 different ones. PMDX.COM - Products for CNC and motion control applications
And Mach4 is a CNC Control program, not a CAM program.