PayPal Smart Payment Buttons enabled your site to accept PayPal payment from your customers without leaving your site.

Why PayPal Smart Payment Buttons:

• Accept PayPal and/or all major credit and debit cards – Visa®, MasterCard®, American Express®, Discover®, Diner’s Club, and JCB
• Accept Venmo (U.S.Only), presented automatically to cookied Venmo users.
• Accept PayPal Credit (U.S. only): You get paid up front; customers get time to pay.
• Accept payments in almost any currency
• Reduce security worries because payments are processed on PayPal servers.
• Allow customers to check out without a PayPal account.
• Provide customers with a fast, seamless checkout experience.
• Charge orders immediately or authorize and capture directly from your site.

Setting up PayPal Smart Button:

Please follow the video to create a PayPal app and get credentials:

As you have seen in the video,  to go the app list:

Get the client ID and Secret:

Now, go to your site Admin Menu >> Downloads >> Settings >> Premium Packages >> Payment tab:

Copy "Client ID" and "Client Secret" from your PayPal app to premium package PayPal config options.

And get your sandbox API credentials from here https://developer.paypal.com/developer/applications/

Finally, click "Save Settings" button and it is ready.