You connect your iCloud calendar with an app-specific password from Apple. Your normal Apple password does not work here and you never hand it over.
- Sign in to your Apple account and choose Sign-In and Security, App-Specific Passwords. Two-factor authentication must be on for this.
- Create a password with a recognisable name and copy the code.
- Here, click Connect a calendar, enter your iCloud address and paste the code with the dashes.
If you change your Apple password, Apple revokes all app-specific passwords. Connect again in that case.
Good to know
You can see attendees and your answer to an invitation here, but you change them in your own calendar app.