As an former administrator for GitLab enterprise I can say for closed source development it is an amazing tool to have. It does however have limits. For starters you will need to bother your unix administrators to assign a license to you. And after that happens the same guys start getting cranky if you use git LFS(Large File Storage) or manage a couple repos about ~100MBish. if you fork open source efforts remember to git clone --depth 1 ! As a free user of GitHub , I don't get crazy CI pipelines or crazy project management tools. I also don't need it !
I use the opensource version of gitlab and it works happily with AD. I never used the CI/CD stuff. we have jenkins/Nexus for that. If you like you can add your public sshkey for passwordless login. we have 30 users, never had to do any additional management to add users. So what else do GitLab enterprise give me.