You do need to preregister for all live stream classes. The sign up cut off time is 5 minutes before a class starts. You will get 2 emails or texts. The first one confirms that you are registered for the class (that one is sent automatically and immediately). It is sent from email@example.com and contains the link you need to access the class.
The second message is sent as a reminder 15 minutes before the class starts. It also has a link to the class.
Double check Spam/Junk folders in case the emails goes there instead of your inbox. Better yet, add firstname.lastname@example.org to your email address book and/or mark us as a “safe” sender.