So I am trying to create my Sims who I plan to make him a mega wall-street-type yuppie, but I am trying to create his outerwear item. So I was thinking about getting him an overcoat suit & tie type look.

I think The Sims Store Fifth Avenue Fashions series have some amazing pieces, especially their Overachieving Overcoat, their A Fella's Trenchcoat, and their Buckles and Buttons Overcoat.

The only issue is that none of these items are in the outerwear category which I find very strange. In real life, you would never wear a trenchcoat in the summer unless you are a complete weirdo, and you would never wear an overcoat unless it snows, but yet, the one category these items are suited for is not available in that category.

So currently I have to settle with the Wool Trench Coat on the Sims 3 Store's Mother Russia series.

Now, if there is a user friendly way (because I'm a complete boomer, level 10,000) to edit the clothing categories of items on The Sims 3 Store, then even if I decide to keep my yuppie Sim's Russian Wool Trench Coat, I can have another yuppie looking outerwear item for him.

I appreciate the help.

This is quite similar to your original thread, and so the answer is very similar.
If you want to convert these items to .package format as discussed there, you will need to use S3RC to remove the encryption. You just drag and drop file onto the s3rc.exe and a black window will pop up for a brief second and that's it- it will now be editable in S3PE when converted.

If you were using EasyCASP, it should be able to see these items under 'Installed Content' as before.

This is probably going to sound incredibly boomer, but where do I drag it from if it is a Sims Store content?

You will need the original download file, which will be a .sims3pack. If it is no longer in your My Documents > The Sims 3 > Downloads folder, you can redownload them from your Purchase History on the TS3 store website

OK, so I've downloaded the S3RC, and I see two applications (attached).
Both of them when I click on, have a black screen flash before me and then nothing.

I'm probably doing something incredibly boomer but do you (or anyone else here) know what's going on?

Neither program needs to be opened (nor can be).
As in the first reply, all that is required is to drag and drop the piece of store content (either in its original sims3pack, or after converting it to a package using Delphy's installer from the previous thread, either will work) directly onto the one called S3RC. A similar black window will pop up for a moment and disappear and that's actually all it needs to do These are basically just little scripts that do their thing without any interface.
The file will then be the same as any other CC and editable in all the same ways.

Thank you soo much. I was literally about to look even more stupid and even more of a boomer by asking a follow up question, but I figured it out.

It is so counter intuitive; it is literally dragging that package file, moving it over and placing it on top of the S3RC application icon. Who would've known

Thank you.