There are two possible options to connect your PayPal account - Option 1: NVP/SOAP (classic integration) and Option 2: API REST V1.
We recommend trying NVP/SOAP (Classic) first. In case you have issues with getting payments through this integration (it is usually related to some requirements PayPal applies to countries where an account is registered in) you can try API REST V1 integration.
Option 1: PayPal NVP/SOAP (Classic) Integration
Option 2: PayPal API REST V1 Integration