As indicated at the ST community wiki and in my thread, the ecobeeSetZoneWithSchedule was designed to work only with myEcobee device (available at my store). Refer to the prerequisites section:
The smartapp cannot work with the ST stock device or any other DTHs as MyEcobee device is the only ecobee device that knows the complete list of active ecobee climates/programs running at your home and which one runs at a given time.
So, if you want to use the smartapp, please purchase MyEcobee device at my store.
Also, if you have any questions about my DTHs or smartapps, please send your questions to firstname.lastname@example.org as it’s easier for me to respond to your requests through gmail conversations. I’m able then to get the user context and history of each conversation.