I have created “Administrator” user. When the admin try to “Create New book”, we get this message “Registration has been disabled”
How do I allow the administrator to create new book.
You should consult the WordPress Multisite docs. It looks like registration is disabled. https://codex.wordpress.org/Network_Admin_Settings_Screen#Registration_Settings
Thank you and changed the settings to “Both sites and user accounts can be registered” and it works.