You can add your PayPal merchant account in the following ways:
1. Visit your Settings page and click the "Payment Gateways" tab. Scroll to find the "Inactive Payment Gateways" sections and click the "Add" button under the PayPal Merchant logo.
2. When you create a plug you be provided with the option to attach your PayPal merchant account similar to above.
How it works
1. Click the "Add" button below the PayPal merchant logo, read the instructions in the notification box and follow the process to be redirected to PayPal.
2. In the PayPal form enter your PayPal account credentials and login.
3. In your PayPal dashboard click the "Grand Permission" button.
4. Once permission is granted, you will be redirected back to plug&paid and your PayPal merchant account will be attached and ready to use.