The install manual in (https://docs.gitlab.com/ce/install/installation.html)
implies that the default user for installation should be ‘git’.
However, durnig some of the stages the following message is displayed:
You are running as user git, we hope you know what you are doing.
Things may work/fail for the wrong reasons.
For correct results you should run this as user gitlab.
Also, user git will usually not have a home dir, which has to be created as part of the manual…