Register Popup does not work

Hi I am stuck as the Registration Popup does not work.

Please see the screens on this link.

https://bestbidonline.co.za/registration-login-display/

ERE just shrug their shoulders and say it works with other themes.

If you click for example My Properties on https://www.bestbidonline.co.za without being logged in you get an error message as follows.

https://bestbidonline.co.za/my-properties/

When you click on Login or Register on the error message you get a Popup with Login and Register tabs.

When u click on Register it gives a faulty display and you cannot proceed…..

I need urgent help as I cannot continue until this problem is fixed.

I know it is a Plugin function but ERE just shrug their shoulders and say it works with other themes???

Thank you

The page I need help with: [log in to see the link]