As you already know, Read/Write/Delete/Permit are the only permissions Egnyte offers as of now.
This feature was requested by users from other Egnyte accounts too. We already have an open ticket with our development team for enhancement. You can subscribe to the What's New section on our helpdesk to get regular updates about the feature releases.
PS. Help others find answers by selecting "Accept as Solution" if a post answers your question."