The 'Require Access Passcode' feature creates an additional layer of security. When enabled, the host creates a Passcode. All guests must be given this passcode to access your Event. Note, this is a different code than your 'Event Code'.
The 'Require Access Passcode' feature is available in the Premium and Premium Plus plans, and is listed in the Premium section of the settings.
For the Host to enable this feature, click to display the checkmark, as shown below.
Enter a Passcode and click 'Save'. Then provide the Passcode to all your guests.
When guests access your Event, they will see the following screen. They will be required to enter the passcode set by the Host, and then click 'Join an Event'.