Hey it's been a while and I'm trying to redownload the modder. Haven't been able to remember where to extract the files to specifically. What is the specific place where the modder has to go?

When attempting to launch a custom level, the game doesn't even seem to register the mod and just launches the normal game.

Just extract the zip into the game folder. It should look something like this:

Ah thank you so much. The modder was still in it's own folder was causing the issue.