This is an unofficial LineageOS organization with the necessary patches for full Substratum support. To learn more about Substratum, check out their documentation repo.
To get started with Android/LineageOS, you'll need to get familiar with Git and Repo.
To initialize your local repository using the LineageOMS trees, use a command like this:
repo init -u https://github.com/LineageOMS/android.git -b cm-14.1 --no-clone-bundle --depth=1
Then to sync up:
repo sync -j$( nproc --all ) --force-sync -c --no-clone-bundle --no-tags --optimized-fetch --prune
The extra flags on the repo init command will make the repo much smaller by initializing shallow clones. To pull down new changes, run the repo sync command.
Please see the LineageOS Wiki for further building instructions.