Invite @whatsappbot:polychat.de into the room. (i hope it joins automatically)
within the subroom activate the bridge
create - Create a WhatsApp group chat for the current Matrix room.
and get the invitelinks for the remote room and store it. That will be used for the next user to join the remote-room
invite-link [--reset] - Get an invite link to the current group chat, optionally regenerating the link and revoking the old link.