<?php

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => 'https://a...content-available-to-author-only...l.com/transactions/2020979/status?clientReference=INV-987',
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 0,
  CURLOPT_FOLLOWLOCATION => true,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => 'GET',
  CURLOPT_HTTPHEADER => array(
    'Authorization: Basic alpZMzB5WTo4ZDMwOGI5YWRlOTM0M2M4YmIzOWUzNmUwMzk1Mzk4OQ=='
  ),
));

// Execute request
$response = curl_exec($curl);

// Capture HTTP status code
$httpCode = curl_getinfo($curl, CURLINFO_HTTP_CODE);

// Capture cURL errors
$curlError = curl_error($curl);

curl_close($curl);

// Debugging output
echo "HTTP Response Code: $httpCode\n";
if ($curlError) {
    echo "cURL Error: $curlError\n";
}
echo "Response:\n$response\n";