Problem is when you click on Login / Register in the top area right, you go in the autogenerated “my account” page.
In there, the register button is an empty link!
Of course registrations are setted on “everybody can register” so I don’t really get why it’s blocked!
No, because the plugin throws the JS error that breaks all the functionality on your website and it doesn’t depend on the theme installed. So you need to fix or configure the plugin firstly or try to use another one.