Hi ,
after creating the whitelist, create a "myAllowlist" Group ACL
Within this group in the "Target Rules List" area configure your Target Categories as a "whitelist".
908e8c6f-bf69-4e8b-befd-9bea2260ae96-image.png
At the bottom under "Default access [all]" configure as "Deny".
5f58ee89-7da0-4805-9945-9ff930e81f90-image.png
Save the configuration and after saving, to make the changes operational, go to "General settings" and press the "Apply" button
This blocks all traffic except the whitelist.
I hope it is useful
Greetings and good work