You may want a signatory to send an additional document, such as an ID. You can set this in your transaction if you want to use this option. You can do this by going to the additional individual settings:
You click on the gear behind the person to whom you want to request an attachment. In the menu that opens you can indicate via "Attachments" which attachment (s) you want from this person. You can click "Add" and enter a name and possibly a description. You also have the option to make the attachment a requirement by checking this option on the right. This ensures that the transaction cannot be completed without this signatory uploading the attachment. If you still want to delete the attachment, you can do so by selecting the box in front of it and clicking on the trash can.
Would you like to view the copy ID / attachment before the transaction is completed? You can set this. How to read that here.