You're using tabbed registration and you've fatal JS errors on the page. Those fatal JS errors are blocking the tab JS from working. Within CB > Configuration > Integrations ensure CBs jQuery is enabled and jQuery Migrate is disabled. Looks like you turned CBs off in favor of loading from a CDN. Try turning it back on to see if it helps, but the following errors are likely the cause of your issue.
As for the JS errors they appear to be in regards to 3rd party extensions as follows.
IN: /plugins/system/rokbox/assets/js/rokbox.js
ON: Line 1589
Code:
Uncaught ReferenceError: Class is not defined
That one appears to be coming from something called "rokbox". Appears to be a Joomla system plugin.
Code:
Uncaught ReferenceError: RSFormPro is not defined
This one is inline within your template, but is in regards to 3rd party extension RSFormPro.
Code:
Uncaught ReferenceError: cbjQuery is not defined
That one is because the 2 above JS errors are causing CBs JS to fail to execute causing cbjQuery to not be defined.