To get started with Android/LightningFastRom, you'll need to get familiar with Repo and Version Control with Git.
To initialize your local repository using the LightningFastRom trees, use a command like this:
repo init --depth 1 -u git://github.com/teamorchidos/android.git -b lineage-17.1
Then to sync up:
repo sync -c -d --force-sync -j$(nproc --all)