Hello @GNJRox,
You're on the right track, QuickBooks Messenger is a feature available only in multi-user mode. Let me tell you how you can check any logged-in user in the server.
To start with, the screenshot you shared tells me that you've got a view of it already since it'll automatically turn on once you logged in in multi-user mode. Consider clicking the icon, twice, so you can launch the tool and clicking Chat will let you identify any available users currently logged in in the company file through the server.
In addition, here's an article you can read to learn more about how you can utilize the QuickBooks Messenger tool: Enable and use QuickBooks Messenger.
Lastly, I've also included this helpful article for the steps you can follow in case you'll bump into errors while working with QuickBooks in multi-user mode: How to fix issues when hosting your company file in multi-user mode?
If there's anything else that I can help you with, let me know in the comments. I'll be here to lend a hand.
