There are actually 2 groups you have to deal with. The regular group is positioned on the page like any normal group. Then there is a floating group positioned at the top of the page with the height being the same as the page itself. Set the floating group’s “vertical float relative to” to BOTH.
The floating group is NOT visible on page load. When the scrolling position is greater than or equal to “x”, then the floating group is visible.
The floating group can either have a normal height OR it should be the same as your page’s height. In the 2nd image, you see the “Back To Top” button. That is also in the same floating group.
In regards to you page scrolling, you do current page’s scrolling position is EQUAL TO OR GREATER THAN x. X should be the distance between the top of the page and the regular menu.