Jupiter Broadcasting’s Rooms are organized into groups called spaces and sub-spaces. You join the main JB space to get access to all the rooms, or join a specific sub-space:
For any of these links, you will be prompted to choose a Matrix client to proceed with. Element will be the top option, and is the recommended client for users new to Matrix. If you have not created a Matrix account, you will be guided through creation on Matrix.org’s homeserver.
Matrix.org maintains a list of Matrix clients.
Be warned that not all clients have support for spaces. You may need to log into Element, and join your desired rooms there first.
jupiterbroadcasting.com as the server name.