I think it would be helpful if you state whether you are looking to implement the custom code or create a similar result using the IX2 (Webflow animations).
If custom code then the Codepen has the details already.
If IX2 then you might want to search for “horizontal scroll” here in the forums.
https://discourse.webflow.com/search?q=horizontal%20scroll
Or take a look at Webflow Workshop #105: Creating a horizontal scrolling page without coding - #5 by still_ideas
Happy building!