Downloads on safari

If this is on an iPhone, then when tapping on the zip file in the Files app, it should create a folder with the contents of the zip, named just like the zip file. However, it will not notify you about it or in any way indicate it has done so, it will just create it.

So tap the zip file, and then look for similarly named folder in the downloads folder in the Files App.

See if anything here helps.

https://apple.stackexchange.com/questions/25678/downloading-and-uploading-files-through-safari-ios

https://www.howtogeek.com/fyi/how-to-unzip-a-zip-file-with-your-iphone-or-ipads-files-app/

https://www.howtogeek.com/212703/how-to-open-zip-files-on-an-iphone-or-ipad/