Adding simple regions into Ion via KML for display in Unreal

Hi, I want to create a map of downtown Chicago with some districts. I created a KML file in Google Earth (see below). I uploaded that asset to my account as a KML file. However, the UE plugin doesn’t support raw KML. But when I try and create a Tile from this KML then Cesium Ion complains that there are no models in my KML.

How can I convert the polygons in the KML into models?