The Host Has Not Arrived
We've recently been making changes to some of the security features of our rooms, one of which is requiring that the room owner or someone with host privileges be present to start the meeting. This is true even of unlocked rooms.
We have more information on why we've made this change in our blog post.
If you've verified that you're logged into your account and are seeing the following message, it means the room is not owned by your account.