If you are using the Standard Paypal as the payment gateway with WP Travel plugin then you need to set the IPN and for this please follow below given steps.
- Go to your PayPal dashboard.
- Click on the setting icon and go to “Account settings“
- Go to “Website Settings” which is on the list at the left side.
- Then go to “ Instant payment notifications ” and click on the update link.
- Click on the “Edit Setting” link and add your site link as in the format mentioned: (YOU SITE URL?wp_travel_listener=IPN), Eg: (https://developer.paypal.com/?wp_travel_listener=IPN)
- Finally, save the setting.