To get mods for incredibox you can follow these steps

1. Uninstall incredibox
2. Go to a Youtube video of the mod you want, and there is normally a link in the description to a download page.
3. download the file and extract it (using something like BreeZip)
4. go to the app page in the files and you should see something called "Incredibox.exe" and if you click on it, you will get the opening page of whatever mod you want.

I hope this guide helps to people who are still having some problems with modding, and hope its clear.