WPUF Pro 2.7.0 update already rolled out along some advanced features with it. Social API is one of them which will let your users register/login to your multi-vendor marketplace using their social profiles like Facebook, Twitter, Google Plus and Linkedin.
Navigate to wp-admin->User Frontend->Modules. Find Social Login and turn on the toggle button on the top right to activate this module.
Once the module is activated, you can simply access and configure it from User Frontend Settings.
Configuration & Settings
To configure Social API on your WP User Frontend, Please login to your WordPress dashboard and navigate to Wp-admin→ User Frontend→ Settings→ Social API and Checkmark(√) the indicated option below to Enable Social Login.
Enabling Social Login will add the social icons under the registration form and users will be able to log in or register using their social profiles by clicking those icons.