Website for Learn strategy

I think SAILZING is the best website to learn strategies and more for free.

They have case studies and quizzes, but my account has been a year now and I still haven't received it, That made me unable to take the quiz.
does anyone know why the SAILZING website is not responding to my emails regarding the account?

Does anyone know of any other websites that can provide case studies? Or the best youtube in terms of sailing theory especially ilca.