Save event reads the event id from the Event Details page. It requests the public title, short text, page URL, and schedule. It does not request the online meeting link for hosts.
Cancelled, draft, and unscheduled events hide the actions. The heading says saving adds the event to the visitor’s calendar and does not register them.
The plugin can be placed in the header or the details area. Wix adds it to the first available slot; the site owner can move it.