Contract plugin?

Currently we have advertising contracts which include terms and conditions along with options for which sized ads that a client would like. It’s a very labor-intensive process right now where the client needs to print out the order form from the PDF, fill it in, and then either fax (ridiculous) or email it back to us. I’d like to move this digitally. I’ve looked at a program like https://www.contractual.ly which allows the import of a contract in Word format but doesn’t allow for the user to select items. Funny enough, the custom can CURRENTLY do this on the PDF if they’re techincally adept so I’m wondering if the same tech (modifying PDFs for example) can be done in a more simplified process online. Any thoughts or plugins that you could suggest?

Thanks in advance!