Display content/pdfs after submitting a form?

I wonder if anyone can recommend a form plugin that allows for content to be displayed after a form has been successfully submitted.

Example: This page http://teachhumane.org/heart/humane-resource-guide-download/ has a form on it that will show PDFs after the required form fields have been filled in and submitted.

I saw that Contact Form 7 allows for a page to be displayed – https://wordpress.org/support/topic/plugin-contact-form-7-file-download-after-the-submission?replies=4 – but have been asked to make the content available only after submitting the form and not by way of a direct URL.

Thoughts or suggestions?