RingCentral PHP SDK throwing Uncaught exception InvalidArgumentException on login

Hi All,

I am trying to use RingCentral PHP SDK to send SMS. When I use code from demo then I get error shown in below screenshot. When I use JS SDK with same credentials then I am able to successfully send SMS. Following is my code for php:

use RingCentral\SDK\SDK;
// require_once(__DIR__ . '/vendor/ _bootstrap.php');
require(__DIR__ . '/vendor/ autoload.php');

$rcsdk = new SDK('appKey', 'appSecret', SDK::SERVER_SANDBOX);
$platform = $rcsdk->platform();

$platform->login('sandbox_no', '', 'password');

Please let me know if I am missing something or I need to install any additional component.