So I submitted all of my materials to Andover via the Gateway. However, in Part 2 there is an option to upload additional documents. It says that this is rare. I have nothing additional to share. However, it won’t let me click “Finished” and so the items aren’t showing up as green and checked off. This is driving me crazy because it makes me feel like my application is incomplete. Did anyone else not submit anything here?
Not to worry. Andover told us this was irrelevant and we received an email that the application was complete.
Gateway should fix this, as you’re right: it gives you the impression that your application is not complete for these optional docs.
Oh great, thank you so much. Now I have some peace of mind. 
This happened to me, too. I just left the second spot blank.