@sarah3487 also, is it possible that you have changed the file association? For example, did you ever try to open one of these files and have a box come up asking if you would always like to use "this program" (ie winrar or 7-zip) to open this file type? To which you said yes?
You may need to fix the file type so that it is showing correctly as a .package file again. Here are instructions on how to do that:
https://www.digitaltrends.com/computing/how-to-set-default-programs-and-file-types-in-windows-10/
To double check if this is your issue you can download this piece of CC which is not zipped and is a .package file and then see what it shows as in your Downloads folder. If it IS a .package file, post back here and we will continue looking for solutions for you. If it is something else other than .package you can try the above solution.
https://www.thesimsresource.com/themes/maxismatch/downloads/details/category/sims4-clothing-female-teenadultelder-everyday/title/v-neck-guipure-detailed-dress/id/1402793/
I hope this makes sense...