Registration of participants

I have a zoom pro plan and I am using it signed in on the web but I am struggling to add participants registration to a meeting.
The registration check box is there only if I don't make it a recurring meeting. As soon as I select recurring meeting the registration check box disappears. 
And even when there is a registration chcekbox, when I select it, no other tabs appear, so I cannot see options to select questions etc. That whole seciton (including tabes for email and branding are missing). 
Any ideas?