No, you do not need to sign up again. You are already signed up for the beta program.
Nobody received any notification of closure. By the beta program being closed, it means no new and additional users can any longer sign up to the program. They released the official build in Korea and it had major problems. The article states that the beta program was reopened to additional users in Korea because of these issues. Nobody in the US received the official software update. We will either get another test build, or have to wait a little longer for the official software while Samsung irons out any bugs in Korea.
