I was wondering how we can add other people into our projects
so at the left side, there is a button above the "settings" button. once you click that, then you can press the "start session" button to create a multiplayer session. image below
once you create the session, you can obtain the link for the session by clicking on the "plus" button (shown below)
as of now, you cannot permanently add people to your projects. you yourself have to have the editing tab open as well. however persistent multiplayer sessions will be implemented sometimes in the future.
hope i could help :)