Even if it is not said, only those who are selected based on the satisfaction and direct management of the host can participate, especially for remote courses.
Access is accepted or denied, sometimes you are deleted after you have entered and also selected to have greater control in managing the meetings and the participants, who are a unique group of people. It can't be easy as the host alone leads all the meetings and I understand this defensive behaviour. Since they are mainly speeches, I have always appreciated them. But Vipassana is a meditation technique that doesn't need convincing, but only experimentation... nevertheless I found them interesting. Such a control management related to vipassana meditation means that these meetings are ultimately reserved only for a group of people, therefore nothing universal. I wish everyone a good continuation in the Dhamma..