Is there a way to add KMZ files to Web AppBuilder for ArcGIS?

Answer

Yes, there are two ways to add KMZ files to Web AppBuilder for ArcGIS. Although the Add Data widget in Web AppBuilder for ArcGIS does not provide the option to add KMZ files to the map, the KMZ files can be added via ArcGIS Online or Google Earth. To do so, follow one of the options described below:

Add the KMZ file to ArcGIS Online

Note:
KMZ files are the compressed, zipped versions of KML files.

1. In ArcGIS Online, click Add items and upload the KMZ file to My Content.
2. Open Web AppBuilder for ArcGIS and add the KMZ file from My Content through the Add Data widget.

Convert the KMZ file to a KML file in Google Earth

1. Open the KMZ file in Google Earth and save the file as a KML file.
2. In Web AppBuilder for ArcGIS, add the converted KML file through the Add Data widget.

Note:
For more detailed steps on how to add data to ArcGIS Online and Web AppBuilder for ArcGIS, refer to ArcGIS Online: Add items and Web AppBuilder for ArcGIS: Use the Add Data widget.