Laravel 5 file Download Failed Issu

I`m new to laravel 5.4.and i need to download few PDF files from its database.but issue is when i download here is the issue.

Here is my controller.

 public function download_files(){

    $dowaloads=DB::table('dowanloadable_files')->get();
    return view('dowanload.dowanload', compact('dowaloads'));
}

Here is my view.