The "CustomService.ino" example mentions the "Not Supported" message. Perhaps looking at that example will be helpful:
// This brief sketch demonstrates how you can use HomeSpan's Custom Service and Custom Characteristic features
// to create a Pressure Sensor Accessory that will be recognized by the Eve for HomeKit App. Note that the
// Apple Home App will show this as a "Not Supported" Accessory Tile indicating it cannot be used in the Home App.
// However, this does not create any problems or errors in the Home App.