As an FYI to everyone using this plugin: If you want to give all logged in members access to this feature DO NOT use the everyone group, use trust_level_0. It was non obvious to me until I read that the everyone group actually includes even non-logged in users and that it’s generally not appropriate to attach permissions to this. (In practice, associating the calendar permissions with everyone does nothing at all - new users will be unable to access the feature.)
The plugin might do a better job of 1) eliminating everyone from the selection, 2) having some note to the admin to use trust_level_0 if that is their intention.
Or Discourse could change their APIs to remove the everyone selection to make it more natural for plugin developers to offer the right options.
Cheers and thanks for the plugin. Very useful in my community!