Connecting PayPal Personal account:
In your PayPal account, go to Summary => Seller tools.
Click Update in your API access settings.
Proceed with Manage API credentials.
Copy your API Username, API Password and Signature.
Connecting PayPal Business account:
Visit your PayPal account and go to Profile and Settings.
Proceed to My selling tools. Find API access option and click Update.
Go to Custom checkout experience -> NVP/SOAP API Integration (Classic) -> Manage API credentials.
Copy your API username, API password and Signature.
Go to WooCommerce -> Settings => Payments to enable PayPal as your payment gateway.
Add your PayPal email, API username, API password and Signature.
Please make sure you have the correct settings on your PayPal account like it is shown below:
Go to Seller tools:
Go to Seller preferences -> Block payments: