April 2019
I already have custom content in my game and I regularly update it and keep track of it but today I downloaded a bunch more and I noticed a lot of stuff isn't showing up. Stuff I had previously downloaded was still there but the new stuff wasn't. I took a look at the files and I think this is happening because it's not a package file but I'm not sure how this happened or what to do to fix it. Stuff was downloaded on multiple site, even tsr, most stuff was only one file, not a zip. I'll include a picture of the other type of file there is instead of being a package file.
April 2019
You need to unpack the files using WINRAR.