PayPal
The PayPal module implements the Payment, Config, PaymentMethod and Authentication extensions.
PayPal allows for one-time payments as well as subscriptions.
Payments can be made as installment payments or "instant transfers".
The module offers additional options such as refunds or tracking.
Setup
Apply for a PayPal Merchant/Business Account.
Setup new Application for Hostinger.
Select Live Mode.
Create new Application in the Developer Dashboard.
Copy API Credentials for Application.
Insert Credentials into Provider Settings.
Webhook
PayPal offers the option to use the modern Webhook protocol instead of the outdated IPN protocol.

Sandbox vs Live
The difference between Sandbox and Live is that Sandbox does not allow real payments. This mode is purely for testing and is not suitable for production use.