Di sotto riporto il codice che ho preso dal kit sviluppatori PayPal.
Ho fatto la prova e funziona.
Visto che sono una pippa in .js qualcuno mi sa dire come gli devo passare l'importo corretto?
Grazie.

codice:
<div id="paypal-button-container"></div>


<script>


    // Render the PayPal button


    paypal.Button.render({


        // Set your environment


        env: 'production', // sandbox | production


        // Specify the style of the button


        style: {
            label: 'checkout', // checkout || credit
            size:  'small',    // tiny | small | medium
            shape: 'pill',     // pill | rect
            color: 'blue'      // gold | blue | silver
        },


        // PayPal Client IDs - replace with your own
        // Create a PayPal app: https://developer.paypal.com/developer/applications/create


        client: {
            sandbox:    'AZDxjDScFpQtjWTOUtWKbyN_bDt4OgqaF4eYXlewfBP4-8aqX3PiV8e1GWU6liB2CUXlkA59kJXE7M6R',
           
        },


        // Wait for the PayPal button to be clicked


        payment: function() {


            // Make a client-side call to the REST api to create the payment


            return paypal.rest.payment.create(this.props.env, this.props.client, {
                transactions: [
                    {
                        amount: { total: '0.01', currency: 'EUR' }
                    }
                ]
            });
        },


        // Wait for the payment to be authorized by the customer


        onAuthorize: function(data, actions) {
            return actions.payment.execute().then(function() {
                window.alert('Payment Complete!');
            });
        }


    }, '#paypal-button-container');