I want to set the value inserted in the "CustomFieldSuite" of the WordPress plug-in to the permalink.

We are building a site using the WordPress plug-in CustomFieldSuite

Custom Posts use CPTUI as "merchandise"
I applied CFS to it and created a field called "num", and I want to slag the value I set for that num field.

Example) Value for https://xxx.com/merchandise/num

I've looked into many things
br/> I am troubled that only the example of the similar plug-in AdvanceCustomField is listed.

I thought you might use an action hook, so I wrote
in function.php. https://mgibbs189.github.io/custom-field-suite/api/save.html
I tried to save the value as shown here, but it didn't work out well.

If anyone knows, I would like to ask for your help.
Thank you for your cooperation.