Hopefully I posted in the right forum. This isn't Sims-specific but only has happened with two bits of CC for TS3.

Basically, I get an error either of the "no files found" sort or the "error" sort (the latter won't tell me anything about what's wrong).

So far it's happened with this and this.

Can anyone tell me what I'm doing wrong? I've tried everything I can think of. This might happen with other .rar files (Sims or not) so I'm trying to find something that'll keep working.

Edit: solved, found a solution myself because I am an idiot and didn't look thoroughly enough ( https://macitbetter.com/ )

Try 7-zip. Most "error" files I've come across have been openable with this program.
https://www.7-zip.org/

I tested it out on Silverowl's file, and my regular unzip program gave me an error, but the file opened fine with 7zip. I think it has to do with files being packaged with older or newer programs, or in a slightly different packaging format that some unzip programs can't handle.

Does this come in a version compatible with Macs? I looked at it and didn't see an option for Mac but I might be missing something. (Right now I'm using Keka)

I haven't touched a Mac since 2008, so... no. But maybe someone else knows.

I would've been the same if I hadn't gotten so used to my old school's computers (they were all macs, all of them). I kept searching while waiting for replies and did eventually find something I hadn't seen before though: https://macitbetter.com/

Opened both files no problem and will hopefully open other files I'd normally have a problem with.