Navigation up and down arrows between sections

Hi! On my new landing page that is under construction I want to implement arrows on the bottom right side. With this arrows it should be possible to klick the down arrow to come to the next section below and when you are not on the top section there should be the up arrow to klick to the next section above.

A example for this is Polywork with the arrow that appears in the middle and moves to the right when you come to the second section:

The important difference: I want that the same arrows are staying in the bottom right corner so that they are always in the view.

My question: How can I implement those arrows? Because it`s a one pager it should help visitors to click trough the different sections with just a klick on the up or down arrow.

Thanks in advance for your help!

Here is my public share link: