I didn't do a LOT of research, but what I found on a STDR-4C shows a USB SmoothStepper inside, and yes, a Gecko G540. So from this I'm guessing you either have a version of the STDR-4C, which seems to NOT be available now, with an ESS or you've put an Ethernet SmoothStepper in the box in place of the USS. I guess in either case, this is why the manufacturer can't help and/or why their plugin doesn't work. Also everything I found on the STDR-4C shows Mach3.
If this is a customized machine, you'd be best off just following thru the Warp9 setup and create a profile FROM SCRATCH. That would get the ESS working, but you'd have to figure out things specific to your machine like home/limit switches and the spindle and perhaps even ports and pins for the motors. Perhaps you could load the manufacturers profile and check in the ESS and Mach4 setup and jot down things like home and limit switches and stuff and manually enter these in your now custom profile.
You might have to either start with the manufacturers profile and fix it or start from scratch and figure everything out.
The machine manufacturers web site seems pretty professional, so one would HOPE that their support would help you get it figured out. Unless you bought the machine used or in parts or a basic machine without the controller and you're setting up the controller, in which case the manufacturer would be stuck, too. There's a lot to know here but there ARE resources to help. Here is only one and because we don't know your machine setup, it's hard for us to help!!
So the G540 docs, the ESS setup stuff, and Google/patience. Hang in there, you have what seems like a nice machine so the end result will be worth the effort.
Like I tell my grandkids, if it was easy, anybody could do it!!
Tom