I do not have an invite key yet

Ask the room host for a 4-character key, or join directly from the event QR or share link. Joining the room is separate from dashboard sign-in.

I already joined but cannot sign in

On the sign-in page, use the same email you use in RoomStamp, or use Forgot password for a temporary password. If you are already in the room on another device, open Settings there, tap Copy sign-in link, and complete email and password on this device.

My key says invalid

Check for typos and make sure the room is still open. Invite keys are room-specific.

I am using a new browser or phone after joining

From a device where you can still open the room, go to Settings and tap Copy sign-in link. Open that link here, then enter your email and password. If you never saved a password, you will set one on that page.