"SSH Keys" setting can be hard to find
https://docs.gitlab.com/ee/ssh/README.html under "Adding an SSH key to your GitLab account", step 4 is "Click SSH Keys". If your browser window is quite wide, text headings are added to the icons in the sidebar to the left side of the "Settings" page. Otherwise, there are only icons, so the words "SSH Keys" appear nowhere on the page, and not even a search of the page for "SSH Keys" will turn them up.
It took me a few minutes to realize I needed to look through the icons on the left side. Perhaps step 4 could be modified to read something like "Click SSH Keys, found in the left-hand sidebar".