Mabye you have to build it. Maybe is created on-demand.
I have see some info about this path: "path/to/ts3/server/directory/query_ip_whitelist.txt" so that means the root of the ts3 install dir (on each user).
Something like: "/home/user/ts3/query_ip_whitelist.txt".
If that don't work, ask for developer of the webinterface because will know for sure.
Also you can use other like solutions
http://tsstatus.sebastien.me.
Regards.