This addon by nature should work just fine but for those having issues please attempt the following fixes/suggestions below before asking for help.

Here's a few fixes or suggestions you could try to get this addon working, as well as a few things that may be causing issues.

1. Addon confliction - Try uninstalling other addons to see which one is causing issues for you. This addon should be compatible to most on the workshop.
   
2. Verify Game Files - Navigate to your steam library, right click "Garry's Mod" and click "Properties...", click on the "Local Files" tab and choose "Verify integrity of game files...". Wait for the download to finish and try using the addon again.
   
3. Accessing Correctly - Make sure you are for one typing the correct commands into you client console not your server's. You may also need to make sure you have admin permissions to access the menu but can be turned off once accessed.

If none of these fixed the addon feel free to drop your issue below and I'll help you the best I can.

Thanks for the support