Once activated you will also need to activate one of the three integrated contact form plugins: Gravity Forms, Ninja Forms, or Contact Form 7. Please read the respective documentation for further configuration options for each plugin.
Once you have configured your forms, head back over to "Job Listings > Settings" (and "Resumes > Settings if active) and assign a form to the respective settings.
That's it! Please note that beyond this point the theme is not responsible for any more functionality in the plugin you choose to use. Any functionality such as notifications, collecting/sending additional information should be handled through the contact form plugin itself and is not related to the theme.