For informal exchanges, share practical info and help organizing some stuff, we use a chat. It's a useful tool for us for more direct connection, however, important subjects and decisions will still happen in meetings through live discussions.
We want to have at least one direct connection with people before adding them to the chat. So if we haven't met yet, please either visit us or contact us by email at magari[(at)]eauchat.org to join our next call.
Then if you don't already have a matrix account, you can visit https://app.element.io/ to create one, and then send us your matrix username (or even better, the full id) by email, we will add you to our chat room.
Sometimes, we create some specific chat rooms to work/organize on some subjects. This is done informally, so if you hear about one of them, you can tell us through the main chat or by email, and we'll add you to that channel.