You're welcome to participate! It's for the dissociative *community* (emphasis on community) so no, you don't need to identify with a specific disorder to be a participant, just that you identify with the community and its experiences (of various forms). Personally, I am not diagnosed officially, so it would be hypocritical to expect that from the other participants.
The part about DID representation in media is more of a "reasoning for creating the jam" and a hope that the content from the jam will counter some of that bad rep. Not the entire goal of the jam, but more like a guiding factor.
I'd be happy to hear more about your experience and see what you make for the jam!