Script running, no change to calendar

[jason-d-man]

UPDATE: I hadn't added the services, and now I have and it's working great. Sorry for the bum steer.

I followed the instructions to install this marvellous script and although the Execution Log says it runs fine, I sadly see no change to my Google Calendars.

Are there more detailed instructions or common mistakes I can follow to check I've set this up properly? It seems a lot of people have got it working so I'm hoping it's something simple I can fix.

My intention is to import an Airbnb calendar into a Google Calendar and then use IFTTT to generate a new booking notification, and I'm testing it by using the script with a test Apple Calendar shared calendar, but to no avail. Any help appreciated!