1. Go to this page and download the library: Download understeam/yii2-fcm 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/ */
understeam / yii2-fcm example snippets
...
'components' => [
'fcm' => [
'class' => 'understeam\fcm\Client',
'apiKey' => 'your API key', // Server API Key (you can get it here: https://firebase.google.com/docs/server/setup#prerequisites)
],
],
...