In order to make integrated payments and subscriptions work, you will need to setup stripe and/or paypal. Stripe/Paypal will handle all sensitive credit card information and payments so there's don't need to worry about security.
Guide on how to set up paypal can be found here, and one for stripe here.
After payment gateways are set up, you can create billing plans from "admin -> plans" page, this will automatically create billing plans on all currently active payment gateways.
Important:
If you enable payment gateway after creating plans, make sure to click "sync" button in "admin -> plans" page, this will sync billing plans between your site and all currently active payment gateways.
