The addon was made before the advent of the local calendar in Home Assistant and is meant as an alternative to the calendar integration. So no, won’t work with a local calendar.
In this thread it is mentioned there is an undocumented api endpoint for the local calendar for which you could set up REST api calls. You could go that route or if you want to use my add-on then follow the docs about apple icloud that are available on the addon’s github repo.