1. Go to this page and download the library: Download checkout-bundle/checkout library. Choose the download type require.
2. Extract the ZIP file and open the index.php.
3. Add this code to the index.php.
<?php
require_once('vendor/autoload.php');
/* Start to develop here. Best regards https://php-download.com/ */
checkout-bundle / checkout example snippets
html
public function registerBundles()
{
$bundles = [
.........
........
.........
new Checkout\PaymentBundle\CheckoutPaymentBundle(),
];