If it helps you any, I am using a combination of these plugins:
1. List Subpages
https://wordpress.org/plugins/list-sub-pages/
2. https://wordpress.org/plugins/simply-attached/
It's not as elegant as WPFB because you cannot assign categories, and I have page hierarchies that I have to keep. But it's working here:
http://www.idylwood.org/online-documents
It's better than nothing and heh, it WORKS!