The registration page is a special page where users can create an account on your site. The theme extends the registration form with social networks registration and Captcha protection.
To change the default WordPress registration (on backend) to configurable form (on frontend, screen above) the BuddyPress plugin is required. The plugin is available for free in wordpress.org repository. You can download it or install directly from the WP admin panel › Plugins › Add new panel.
The BuddyPress is one of the most popular WordPress plugins so you will easily find a lot of useful tutorials about it. It offers also tons of free addons you can use to extend its core features.
Official page: BuddyPress Codex
To enable registration, please go to the WP admin panel › Settings › General page and make sure you have the option anyone can register checked.
For multisite/network installation, please go to the WP admin panel › My Sites › Network Admin › Settings page and make sure you have the option User accounts may be registered checked.
Activate register page
After you have enabled registration, you can create the required pages and assign them to the Register and Activation components. in the WP admin panel › Settings › BuddyPress tab and assign required pages (screen).
Customize register form
To add/remove fields (screen, point 2) to your registration form, please follow the BuddyPress official guide.
Register with social network
To allow users to log in using social networks (screen, point 1), the Snax plugin is required. It's optional login method, you don't have to use it.
To set up the social networks, please refer to the Login with social networks page.
Protect with captcha
To protect your register form with Google reCaptcha (screen, point 3), the Snax plugin is required. This protection is optional but we strongly recommended to activate it.
To activate the captacha protection, please refer to the Captcha protection page.
To use a sidebar (screen, point 4) on the registration page, please make sure you have enabled the WP Admin > Appearance > Customize > BuddyPress plugin > Show sidebar on BuddyPress pages option.
Widgets in that sidebar are from the WP admin panel › Appearances › Widgets › BuddyPress sidebar.