Edit file File name : index.php Content :<?php require_once('braintree/lib/Braintree.php'); Braintree_Configuration::environment('sandbox'); Braintree_Configuration::merchantId('d68m73wzrttmy8t9'); Braintree_Configuration::publicKey('h7c2bm97b72bm9fd'); Braintree_Configuration::privateKey('67cf79121710d11dfe308c95c8bb3987'); $btClientToken = Braintree_ClientToken::generate(); ?> <html> <head> <script src="jquery_popup.js"></script> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script> <script src='https://js.braintreegateway.com/v2/braintree.js'></script> <script> braintree.setup( '<?php echo $btClientToken; ?>', 'dropin', { container: 'braintree' }); </script> </head> <form id="checkout" method="post" action="result.php"> <p><div id="braintree"></div></p> <p><input type="submit" value="Pay"></p> </form> Save