Signing Tutorial Files

I'm a web design teacher, and I create tutorials that require students to download start files that are zipped.

With current security protocols, my zip files are difficult to open after downloading.

How do I sign a folder so it can be easily opened by my students after downloading? I'm having issues finding information concerning my issue given that I'm not making an app. I just need to identify my files so they can be unzipped from an identified developer.