Gallery2 + Wordpress: Users cannot upload images

I have installed Gallery 2 and Wordpress 2.0.7 with the WPG2-plugin for a small organization (use: static info + events blog + image gallery).

All our blog authors/editors (several) are now automatically Gallery2 "users". None of them can upload images to Gallery2, though. Why?

How do I allow "Gallery2 users" to create top level shared folders? I don't want to give Gallery2 admin rights to all, and I do not want personal folders on our collaborative site.

Thanks