The preferred method of installation is to use the Billplz PHAR which can be downloaded from the most recent GitHub Release. This method ensures you will not have any dependency conflict issue.
You should received billplz.phar file which you can include to your project.
To start using the library, you can first require the file in your project.
<?php
require "billplz.phar";
$client = Billplz\Client::make('your-api-key', 'your-x-signature-key');
// ...Please go through jomweb/billplz for full documentation.