To make your setup completely automatic you will need the following steps.
1) You will have to code an → UPLOAD-BUTTON ← and connect it to your form-submission.
2) User will fill out all the fields and attach a file (for example pdf-file or similar).
3) The upload then will go to the Wix-Media or Wix-Content-Manager, once the user has completed the form and clicked onto the submission button.
4) Once uploaded the file you get the corresponding file-URL, now you can use that file-url and save it inside of the contact’s extended field.
So when you open the contact, you should see that attachment (URL).
a) ABOUT —> EXTENDED FIELDS…
b) ABOUT —> WIX-MEADIA…
c) ABOUT —> WIX-FORMS…
So now all your users would be able to attach files by their own to their submissions and you could directly check the url inside the extended field (clicking on it or at least copy and paste to get a look onto it). Now you as the OWNER can decide if you want to approve that new contact/member, or not, after reviewing his attached document.
Even this last step could be automated aswell, but this would need a lot of coding. So the last approvement step will still be on you —> you check the attachment and decide what to do → approvement or declinement.
The following links, could also help you —>
…and you surely will find more informations about your issue, or at least posts which are connected to your issue.