In a room you can invite others by using thebutton at the top of the screen.
This will give you a few different ways to share your room:
Room link: This will give you a URL link to the room, you can copy or tweet this link to share it with others. They simply need to visit this URL to join.
Six digit code: This six digit code that expires every 72 hours. To join a room with a code, visit hub.link and type in this code.
Embed link: (Only displayed to those with room permissions). You can use to this embed a link to your room on a webpage, remember everyone with access to the site will be able to enter the room.
The "Notify me when others arrive" checkbox (displayed if you have room permissions) enables you to sign up for notifications when another user enters the room. You can sign up for notifications on your phone or desktop. You do not need to remain in the room to receive notifications.