1 Div changing photo on scroll; Mobile

Hello there,

I am looking to create a similar animation and structure to this site: https://jams.basicagency.com, but ONLY the mobile version of it. It seems to have a fixed div on the left side and a scrolling rolodex of links on the right and as you get to certain links, the images in the div on the left switch. I have no idea how to set this layout up in mobile and would truly appreciate any help I can get. Thank you so much!