How to download from private// following a link?
Thanks to @Kevin, I updated my code to

function amap_file_download($uri) {

  $sFileName =  \Drupal::service('file_system')-&gt;basename($uri);
  return array(
      'Content-disposition' =&gt; 'attachment; filename="' . $sFileName . '"',
  );

}


And it works!