Fill out release form before files can be attached NSFW

Hey everyone,
I’m working on a fashion magazine that takes submissions from artists and photographers – numinousmag.com. This is site we’re bringing into WordPress. On the submission page, we require them to fill out detailed release forms before they can submit art. We’ve been having the problem that these people aren’t filling out these two forms and simply sending their art without the consent of others involved.

How would you recommend we go about requiring these people to fill out these forms before they can attach files to send? I seem to be getting a lot of answers about filling forms out before you can download files, but none related to attaching files.

Any ideas and/or plugins to help us do this would be appreciated. Even some ideas on restructuring our practice to better suit WordPress would help (instead of the other way around). You can find the forms they need to fill out here –

https://www.numinousmag.com/submit