This is crazy making. The ArcGIS desktop software - Pro or ArcMap has a "KML" toolset, that should really be called a "KMZ" toolset. These only can make KMZ files. The web software Portal or AGOL can only consume via "Add Data" the KML. What? Here's some functionality that you can't use. That's helpful. I tried saving the layers as kml's in Google Earth but the load of the KML fails in web applications and it will not tell you why. Crazy town!