Everyone (no restriction) is the fully open setting. Choose it when a resource should be available to all users with no conditions — there are no extra checkboxes to fill in.
Who gets in
Everyone — every logged-in user, and even visitors who are not logged in. This is the only option that allows anonymous access; every other option requires the user to be signed in.
When to use it
Use it for resources that are genuinely public, or on trusted internal sites where you don’t need to gate access at all.
Think before you open: because this includes logged-out visitors, only use Everyone where anonymous access is genuinely fine. To limit access to signed-in people, choose WordPress Role, Users or WordPress Capability instead.