How to pass a parameter when downloading a file?

Question

PHP

There is an apk file for the application. It is necessary to implement a referral system. That is, the user goes to the page where there is a "download" button on the link containing the GET parameter ?ref=***. I extract this parameter and how can I pass it to the application so that after downloading the front-ender can receive it? I read about deep linking, but I didn’t find how to implement what I needed.