It looks like the cura resources were pushed to github some hours ago, so here is my attempt at a Linux Cura build. If anybody could test it that would be great. I don't have the printer built yet unfortunately.
I built this in an Ubuntu 20.04 chroot environment using the latest 4.13.x Cura branch as well as the latest in the Makertech Cura resources repo. I don't have the printer built yet to try this on, but I was able to launch it and add the various Makertech printers to my Cura profile (including the proforge 3).
Notes: From a vanilla install of Ubuntu 20.04 (that I ran from VirtualBox) I had to install the package "libnlopt0" and, maybe not required but I installed for other reasons, "build-essential" and "aptitude".