Hey! I don't know if this group is still running, but if you are I know a tutorial that can help you set it up if you are interested? It tells how to open folders for people to submit and if you mess around in the manage members area under "join request" you should be able to allow people to join.
I'm sorry if I seem annoying or anything, but if you are interested then here is the link to the tutorial on opening folders
fc01.deviantart.net/fs71/i/201…