If your selected Shape Layer Type is Geo JSON, this field can be used to provide a URL to the .json file that you wish to use as the shape layer. 

The URL must be a direct link to the .json file and it must be hosted on a web resource that supports Cross-Origin Resource Sharing (CORS) headers. For example, Google Drive, Dropbox, and SharePoint are not supported as these services do not support CORS for use with this visual.