To enable Paypal payment module, navigate Classified Listing => Settings => Payment => Paypal

3.2.1) Enable: To enable PayPal payment check the box that requests you to enable it.

3.2.2) Title: Give the title that it will show as Payment name during checkout process.

3.2.3) Description: Write a description that will show during checkout process.

3.2.4) Paypal Email: Enter the Paypal Email address that you need to receive payment.

3.2.5) Advance option: Check the advance settings which you want to enable. To use Sandbox to test your PayPal payment effectiveness, enable Sandox. Enable IPN and Payment action “Captcha” and others

3.2.6) Paypal API: Enter your PayPal API credentials to process refunds via PayPal. Learn how to access your PayPal API Credentials.

To Enable API, you need to enter API user name, API Pass & API signature.