Re installed via marketplace and same thing. Menu not showing but I can create a link manually to /servers/. #edit# although main menu not showing for me, you have the option to add blocks from side menu #edit#. Server(s) not showing online but offline.
Under Requirements, it says:
PHP 5.6+ - Tested in PHP 5.6, 7.0, 7.1 & 7.2
I am using PHP7.4 and CentOs8 on a dedicated server, I dont know if that (PHP7.4) is causing these issues.