PHP: save a file (generated by aspx) to server

I have an url provided by a wholesaler. Url generates xml file which I need to save on my server. I use PHP - file_get_contents and file_put_contents to do that:

$savepath = "path_to_my_server_folder";
$xmlurl = "";
file_put_contents($savepath.'eurodigital.xml', file_get_contents($xmlurl));

File is generated on my server, but its content is empty. I have no problems with other xml files if I provide direct xml url, but in this situation file is generated by aspx file dynamically. Xml url is actual url I use. When I open xmlurl in browser, xml file gets saved to device.

Can you help me with moving xml to my server? What function should I use? Is it even possible to do that using PHP 5? "allow_url_fopen" is ON.

Thank you in advance!