As of version 2.1.0, the submission form requires users to be logged-in to submit events as a default. Previously, it was open to the general public by default.
The third setting allows finer control over who has the ability to add events to your calendar. The ‘Add Events’ capability is configured in the My Calendar Permissions Settings.
[submit_event] shortcode to display a custom message to users without sufficient permissions:
[submit_event] Hey, you can't submit events! Create an account to submit an event. [/submit_event]