How do we sell zip files to non-tech-savvy people?

We sell a lot of digital content daily in the form of zip files that contain MP3s and PDF worksheets. Our customers are primarily teacher with wildly varying comfort levels when it comes to computers.

The differences in OS, browser, and installed programs make it super-difficult to provide self-service FAQs that people actually use, and our small team is being crushed by daily emails and calls from "frantic" teachers.

How can we scale this better? What can we use instead of zip files?