Commands are executed in-game inside the console. The server admin commands for Unreal Tournament 4 Pre-Alpha are a little different from previous versions of Unreal Tournament, so I’m posting this here in case any UT4 Hub admins need it.
LOGIN
rconauth + password
rconexec adminmenu
Once the menu is up, you should be able to figure things out yourself. Previous iterations of UT did not have an admin menu that I remember.