Try this:
/**
* @param Document $document
* @return Response
*/
public function download(Document $document)
{
$stream = fopen(Storage::cloud()->get($document->path), 'r');
$headers = [
'Content-Type' => 'application/octet-stream',
'Content-Disposition' => 'attachment; filename="' . $document->name . '"'
];
return \Response::stream(function() use ($stream) {
while (!feof($stream)) {
echo fread($stream, 1024);
}
fclose($stream);
}, 200, $headers);
}