Create ssh key pair in the zone (CZ, RZ, or SCF) from which you want to interact with a GitLab repo.
Add your public key, id_rsa.pub, to your GitLab account in a browser.
Test that you can connect to the relevant GitLab server from the zone (CZ, RZ, or SCF) where you'll be working.
Note that $HOME directories are shared across all machines within the same zone. So, if you have accounts on oslic and quartz, following the above steps on oslic will allow you to work with LC GitLab from quartz as well.