To get started with Android/Maru OS, you'll need to get familiar with Repo and Version Control with Git.
To initialize your local repository using the Maru OS trees, use a command like this:
repo init -u git://github.com/deepak-divakar/manifest.git -b maru-lineage-17.1 --no-clone-bundle --depth=1
Then to sync up:
repo sync --jobs=8 --current-branch --no-clone-bundle
See the main Maru OS repository for more info.