private function get_download_html()
{
$html = '';
$file_id = $this->get_field('file');
if (!empty($file_id)) {
$attributes = [];
$attributes['href'] = wp_get_attachment_url($file_id);
$attributes['class'] = 'btn-default';
$html = $this->get_button_html($attributes);
}
return $html;
}