Is there an internal chat feature without using the integration with (Slack/Mattermost), as in the image there is a chat feature but as appears (You don’t have any active chat names.) so how can I activate this feature and use the internal chat with team member without any integration.
I have the exact same question, and 4 years after this question was asked the answer is still somewhat fuzzy. More than that, some people are downright disrespectful when you insist on an appropriate answer (see How to enable chat by @LonelyPixel).
Can anyone point to a document that explains how to populate the User Settings > Chat page?
EDIT: I contacted GitLab support. There is now a GitLab issue on that: #340480
Chat account names appear here when you authorize a chat application at GitLab to run common operations such as creating issues, running pipelines etc from the chat application itself. So, the chat accounts you see here represent authorizations with the chat applications.
Chat page here doesn’t represent an in-built chat application that you can use within GitLab. That said, GitLab comes bundled with GitLab Mattermost which you can use for chat if you would like.