How to make a Smart Slider 3 slider act a fixed menu?

W3Schools has an excellent tutorial on how to create a fixed menu which you can modify to make Smart Slider 3 act as your fixed menu.

You can use the n2-ss-103-align selector where the 103 is your slider ID.

Can I use Smart Slider 3 as a sticky menu instead?

You can follow another W3Schools tutorial. If your slider is at the top of the page (unlike the W3Schools tutorial) you should rather use window.pageYOffset > sticky instead of window.pageYOffset >= sticky

For example:

<script>
jQuery(document).ready(function() {
    window.onscroll = function() {myFunction()};

    var header = document.getElementById("n2-ss-103-align");
    var sticky = header.offsetTop;

    function myFunction() {
        if (window.pageYOffset > sticky) {
            header.classList.add("sticky");
        } else {
            header.classList.remove("sticky");
        }
    }
});
</script>

The 103 in n2-ss-103-align is your slider ID.