?AdminName={VALUE_HERE}
AND
?AdminPassword={VALUE_HERE}
ON CMDLINE
Config file system/killingfloor.ini
[UWeb.WebServer] header
bEnabled=True
MUST BE SET
Create custom commandline, tick the tick box for the two parameters above and specify desired values for both. Make sure you click "save" and restart/reboot server.
Make sure in the system/killingfloor.ini file found in "configuration files" section of gamepanel has the bEnabled=True set under the [UWeb.WebServer] header