Why is registration closed for public?
Do they have a serious problem?
They closed registration currently since they are testing it in a closed environment with a small group of people which is why there isn't any serious problem or anything.
You could have easily understood this if you read the main post thoroughly followed by replies from various posters.
Personally, I took part in this test successfully without a hitch and left a review too. You can contact op if you wish to be a part of the group right here or on telegram.