Get user group's media sources (maybe)

gmsug.php

<?php

$output = 'No Media Sources found';
$fields = array(
    'principal_class' => 'modUserGroup',
    'principal' => $userGroupId,
);

$sources = $modx->getCollection('modAccessMediaSource', $fields);

if ($sources) {
    $output = '<p>Media Source IDs:</p>';
    foreach ($sources as $source) {
        $id = $source->get('target');
        $mediaSource = $modx->getObject('modMediaSource', $id);
        if ($mediaSource) {
            $name = $mediaSource->get('name');
        }
    $output .= '<p >ID:' . $id . ' -- NAME:' . $name . '</p>';
  }
}

return $output;