If you've got Bootstrap running in your template, you could start with any of the copy/paste carousel options you get for free with Bootstrap: https://getbootstrap.com/docs/4.5/components/carousel/
It's a little trickier to set them up w/ 3 "columns" showing and then only scroll one "column" at a time, but it's much easier to do a group of 3 and scroll 3 at a time. You'd just need to replace the HTML inside the "carousel-item" with a row and 3-cols that held your speaker cards.
This'll work in the Marketo editor as well, so it's really easy for someone to come in and update. It'll show up (and scroll) in the LP editor, so you can use the built-in nav to scroll thru the different "slides" and click in to edit each of them as needed.