I'm a new user of pogoplugpro. All working well sofar. However, I have a directory of photo files that I shared with the family. They received email with a link to see the directory via a web browser. This works fine and they can see the photos. Now, they want to upload photos so I can see them. I can't find any button, menu, popup ... that will allow someone I shared the directory with to add a new file. What am I missing?!