1. Go to this page and download the library: Download slince/youzan-pay 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/ */
slince / youzan-pay example snippets
$apiContext = new Slince\YouzanPay\ApiContext(CLIENT_ID, CLIENTD_SECRET, KDT_ID);
$youzanPay = new Slince\YouzanPay\YouzanPay($apiContext);