I hope you all are doing well and staying safe during these times.

I was wondering if someone can help me figure out how to remove the question mark (?) in the URL.

The URL I am trying to rewrite looks like this: /?download

The URL I'd like to have:

That's the code I have tried but didn't work, I get an Internal Server Error

add_action( 'init', 'wpa5413_init' );
function wpa5413_init()
{
add_rewrite_rule(
    'windows/([^/]+)/?/?download',

    'windows/$matches[1]/download',

    'top' );
}

Please let me know what you think?