A few useful answers.

Do recipients need an account? No. They use a private deposit link. Is every document required? Yes, unless the requester explicitly allows a written reason for that item.

Can a document be replaced? Yes, while the request is open. Earlier versions remain in the history. Does uploading finish the request? No: the requester reviews each current submission and marks the dossier complete. Can a link be disabled? Yes, the requester can revoke or replace it.