For this, you need to go to
this project and go to the 'page settings' of the home page. Then, scroll down to the 'custom code' section and copy-paste everything from that project to the 'custom code' section of your project. Publish and the code should now add the 'change slide on scroll' functionality. Note: the code may not work in the designer, but that's normal. It does work on the published site.