Show only on certain pages

Hi friends!

I recently came across this page with details on how to hide the banner on certain pages. I’d like to do the opposite: only show the banner on certain pages.

I tried modifying the code given to the below, but it doesn’t seem to be working for me. Perhaps you could correct my mistake?

add_filter('cli_show_cookie_bar_only_on_selected_pages', 'webtoffee_custom_selected_pages', 10, 2);

function webtoffee_custom_selected_pages($html, $slug) {

    $slug_array = array('manage-cookies');
    if (!in_array($slug, $slug_array)) {
        $html = '';
        return $html;
    }

    // For wild card URL entry
    foreach ($slug_array as $slug_ar) {
        if (strpos($slug_ar, '*') !== false) {

            if (fnmatch($slug_ar, $slug)) {
                $html = '';
                return $html;
            }
        }
    }

    return $html;
}