To get started with Android/ExodusOS/LineageOS, you'll need to get familiar with Source Control Tools.
To initialize your local repository using the ExodusOS trees, use a command like this:
repo init -u https://github.com/ExodusOS/android.git -b lineage-19.1
Then to sync up:
repo sync
All supported devices are built weekly and periodically as changes are committed to ensure the source trees remain buildable.