1. Go to this page and download the library: Download insidieux/slack-api 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/ */
insidieux / slack-api example snippets
$client = new \SlackApi\Client('your-token-here');