Segundo exemplo de auth

auth2.php

try {
    $clientId ='cf8db6fe61bc1efebc6ae4f5ab4af60c';
    $clientSecret = 'f538b73a11eac49827f6da678e859fa7';
    $auth_token = base64_encode($clientId . ':' . $clientSecret);
    $target_url = 'https://apic1.hml.stelo.com.br';
    $ch = curl_init($target_url);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_USERPWD, $clientId . ':' . $clientSecret);
    $headers = array('Authorization=Basic ' . $auth_token);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
    curl_setopt($ch, CURLOPT_FRESH_CONNECT, true);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_MAXREDIRS, 5);
    $response_data = curl_exec($ch);
    $info = curl_getinfo($ch);
    var_dump($response_data);
    curl_close($ch);

} catch (Exception $e) {
    echo $e->getMessage();
}