I personally haven’t explored the document capabilities of “BuddyPress” which is the piece of software, attached to this WordPress site, which constructs all the “forum” functionality. I don’t know where they are stored, how they can be managed, and if it is desirable to start accumulating stuff there. Simultaneous editing isn’t supported and version control less manageable. Because of those layers of uncertainty, my default is to use google, which we know.
@cascadiabrandon has established a google drive folders system under the regernatecascadia.org domain. I just sent you an invitation to the “Bioregional Education Guild folder”. Documents stored there can be shared in a wider variety of ways. Ultimately in our “activist toolkit” I suspect that we will need to suggest and encourage a basic kit of tools and behaviors (particularly for those that play the “secretary” roles in strongly-functioning groups).
For archival resources and out-group collaboration, I personally use https://salishsearestoration.org just because I am committed to the long-term stewardship of that space and it is funded with a governance system that I am part of, but that does not necessarily suit working needs, and has not yet expanded to a Cascadian domain. That is another story.