...to be honest... this may sound cocky or overreactive, and maybe it is; but I don't really want to join the group and just add the art I have as a non-member. I am not proud of the amount of time I've spent on PS-related stuff that in the end I feel was completely wasted, but at least want to allow others to enjoy the couple of persistent things I made, if they choose to do so. So I'll just add my stuff as a non-member, waiting a day between each submission. No big deal.
That said, I don't think I got an invitation. But maybe I somehow missed it or accidentally dismissed it. Or I just forgot.