so you have to start the game server with a user account that have more rights on the file system... i also have this problem on windows... its not an tcadmin problem, its just because the game server process needs more rights on the file system
i have had the same problem! you have to update the Dedicated Server to the latest Version of V2!
http://help.tcadmin.com/Updating
"C:\Path\To\TCAdmin\Monitor\TCAdminUpdateTool.exe" 2.0.62.0