Open a Gravity Form in a Lightbox Popup in Layer Slider

I’m trying to figure out how to get a Gravity Form to open on a page within a lightbox popup. It’s being triggered by a call-to-action button graphic within a Layer Slider.

I’m looking at the Link & Attributes tab on the Layer Slider and I can’t figure out what should be what. Should the class be “open-popup-link” and should the drop down be “open on the same page?” Should something else be filled out? Is any extra code required?

Thanks