This will be something like this: C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\bin\GameConfig.txt
The gameinfo.txt file resides in your root game folder (unless you create a local gameinfo file as discussed in the collaboration section below). So to properly use all the assets available in your game, you will need to edit the gameinfo.txt file to include all of your paths used in mount.cfg. Wall Worm does not use the mount.cfg file. Gmod doesn't use the gameinfo.txt file for game paths like most Source Engine games.
This page details the steps to set up Wall Worm for Garry's Mod in 3ds Max 2018+ using Wall Worm 3.71+.
