OneLinePlayer isn't working, but I've seen it work on Webflow before

I am trying to use OneLinePlayer to create GIF-like videos. I’ve seen it on other Webflow sites, but for some reason, it refuses to work on mine. Here’s the code from the website:

<div style="padding-top: 52.56%; position: relative; overflow: hidden;"><iframe frameborder="0" allowfullscreen="" scrolling="no" src="" style="position: absolute; height: 100%; width: 100%; left: 0px; top: 0px;"></iframe></div>

Look at the Enter Incomes section (other sections are tests of different methods)