When focusing an element, the browser scrolls to that element, messing up your animation.
Place the focus in the animations callback to avoid it.
$(document).ready(function () {
$("#get-started").click(function (e) {
e.preventDefault();
$('html, body').animate({
scrollTop: $("#get-risk").offset().top
}, 2000, function() {
$("#get-started-apply-now-form [name='last_name']").focus();
});
});
});