I read the docs and i can’t find a way to do this. how can I automatically mark a car reservation to calendar with gmail markup ?

So far, I tried the provided code from the example provided in the docs. I used AppScript to send an email to myself but I only have the RentalCarReservation widget on top of the email but I don’t see anything in my calendar.
I was expecting it being automatically added as an event in my calendar.