Required registration link sometimes works, more often doesn't -- why?

I set up an event with required registration.  I see from the  social media metrics interface that at least 300 people have clicked to register, yet no one has succeeded in registering :-(.   When I and others test the zoom link, it sometimes go to the registration page, and sometimes go to "If you are the host, please start the meeting" page,even if it's 1st time someone is on the link. 

Does anyone have any idea why this is happening? and more importantly, how to solve this issue?