For using this repo you need to clone it to the vial-qmk directory. I tested it on the 159c0888457e5675c6dc0a881e7c5bd8b54203e7 commit of vial.
For now it has firmwares for:
For compiling the firmware and setting it on your keyboard you need to download the make and qmk utils.
If you are using the NixOS distro then just run this command in the root of the vial directory
nix-shell shell.nix --run zsh