The theme supports user registration, it is important that you enable the registration option on your website. To do so navigate to "Settings -> General" and enable the option "Anyone can register"
How can users register?
Users can register from a multitude of places, the main ones are the popup login/registration from that can be accessed from the header top bar links.
Alternatively you can also add the "[TDP] - User Profile" widget to any page, which will display a button that opens up the registration popup.