Smooth Scroll Slow Down

Hello,

I've read the posts and added the code snippet to my child theme's function.php file

add_filter( 'generate_smooth_scroll_duration', 'tu_smooth_scroll_duration' );
function tu_smooth_scroll_duration() {
    return 800; // milliseconds
}

But I can't seem to slow down the jump from the top button "Sign up for free" and the optin box it links to at the bottom. It just jumps from top to bottom. I've enabled smooth scroll in customizer but no matter what I set the return to, I'm not seeing a smooth scroll and can't control the speed. It just goes directly from top button to bottom of page.

You can see the live page here:

https://jessicaeary.com/conscious-creator/