Register link not working

After my bosses account was hacked over Xmas we signed mine up for a Pro account yesterday. I have been creating our meeting links for over 2 years now, twice a week.

My consultants can either NOT even get the link activating while I found I can only get the register button to work on Safari.

Is there a known problem?

We cannot find help anywhere.

I have included an image

 They can get no further than this.

what is wrong