To use this script to build roms, include the repo in a buildkite build instance. Please grasp an understanding of rom building, dont assume this will do everything, xda have some great tutorials and guides on building ROMS.
setup-buildtools.sh - Install required build tools on the host
start-local.sh - Start build within the buildkite environment using a specified config
scripts/cloud - Deploy buildkite and building tools to aws and gcloud
See README.md for specific build options and https://github.com/robbalmbra/RomBuilder/wiki/Buildkite-Intergration for a buildkite setup guide.