Takayuki Miyoshi on "[Plugin: Contact Form 7] Need help customizing contact form to allow downloads after user fills in info"

I don't get what is the problem you're trying to solve. Already you have made it possible for only users who entered those required fields to submit and access the attached files.

<p>Your Name (required)
[text* your-name] </p>

<p>Your Email (required)
[email* your-email] </p>