Opencart从网站保存文件

I am creating an add-on for opencart and need to save a file from a website into the admin panel, currently I have the file contents and trying to save into a custom location but every time I run the add on I get an error that the directory doesn't exist.

Here is my code that I am using in the controller

if ($this->request->server['HTTPS']) {
    $url = HTTPS_SERVER;
} else {
    $url = HTTP_SERVER;
}

$file = file_get_contents('Website Link');
$FileDir = $url."upload/";
$fileName = 'products.csv';

if (!is_dir($FileDir) or !is_writable($FileDir)) {
     if (!is_dir($FileDir)) {
         echo "No Directory"; die();
     }
     if (!is_writable($FileDir)) {
         echo "Unable to write"; die();
     }
    echo $fileDir.' - '.$url
} 

the error that comes back is "No Directory" I have echoed out the URL and created a directory at that location called upload and set the permissions for this directory at 777 and still getting the error.

What am I missing?

Im using opencart Version 2.1.0.2