My recommendation is to start with https://github.com/marciot/drunken-octopus-marlin instead. See also https://github.com/marciot/drunken-octopus-marlin/blob/master/docs/FAQ.md and/or https://github.com/marciot/drunken-octopus-marlin/releases.
Marcio was the LulzBot firmware guru and he is continuing on his own. The FAQ referenced above contains instructions on how to build firmware from his repository which is currently based on Marlin-2.0.
If you wish to remain with the LulzBot sources (based on Marlin 1.1.9) you will need the Arduino IDE and either a Linux system or the Windows WSL environment if you want to use the provided build scripts or you can edit:
to build one flavor at a time using the Arduino IDE.
I believe the .config file is somehow extracted from conditionals.h and conditionals_adv.h. I’m not sure how to recreate those two files from the .config file other than manually editing them, but I’ve successfully built firmware for my TAZ 6 without using the .config file.