"Successfully" installed an Audio Unit (AU) plugin with .pkg file but it's missing

I recently bought a set of AU instrument plugins to use on garageband. I've installed it several times and every time it says "Successfully Installed."

I keep trying to find the file/application where I had drag and drop to the applications folder but there was nothing. I checked the Applications folder, "Library>Audio>Plug-Ins> Components" and "Library>Audio>Plug-Ins> VST" but all were empty. I checked my storage as well if it's taking up space since it's 4GB but there was no change. I did the shift+ cmd + . to show the hidden files but there was none and right-clicked to see if the "show contents package" was gonna show up but it wasn't there either.

Then, I also checked garageband if it will miraculously show up on the instruments library but it wasn't there either. (I have enabled audio units on the preferences)

I'm not very tech savvy so I was wondering if there is a step I might have missed?

Thank you.