XSS help

[Chrislinuxos]

I'm doing an ethical hacking test, I tested an XSS payload : on a website, and the pop-up appears, so I want to collect user cookie

I created a getcookie.php file and a cookies.txt file and and I uploaded both files to a hosting server, I placed the two files in the htdocs folder, which now contains index.html, getcookie.php and a cookies.txt

This is the getcookie.php file:

When I try this in the search box: :

I get this URL: https://website2/search/?section=all&query=

and I don't see any cookies in cookies.txt

What am I doing wrong, please? I've tried lot of payloads in the past 3 days but no results, when I type http://website.com/getcookie.php in a new tab, I get the cookie but it's empty, I get this text : Cookie:

Thank you