registration not required?

Do attendees HAVE to register for a zoom event or is it possible for me to send attendees a direct join link or otherwise invite them without them registering?

Background: I am hosting an event that has registration on a different portal and, in the past, we had people register on that platform AND register through zoom which is a lot of steps for them. Is there any way to avoid the second step and just have people able to join the event without registering? 

I have seen the pre-registration option which is possible (I have emails for those who register) but I don't see anywhere if I can continue to "pre-register" people after the event has been published.