In the Sonoran CAD postals plugin config, change the nearestPostalsResourceName value to the exact name of your nearest postals resource.
2. Ensure Proper Startup Order
Be sure that you are starting the nearest-postals addon/resource before/above where you ensure sonorancad in your server.cfg.
Be sure to restart both the Sonoran CAD resource and the nearest-postals script, or restart your server entirely to apply the changes made.
Custom Postal Scripts
This plugin no longer has a "custom" option. If you're not using the nearest postal script, you will need to create an export called getPostal in that script and have it return the player's current postal as a string. Need help? You can always hire a developer.