SBA is not required - none of the modules mentioned in the config settings or the documentation are required.
Documention instructions:
This module supports adding required fields as attributes to your products (you can set them to display only and then modify your template to not show display only attributes). Supported attributes are: Size, Color, Age Group, Gender, Material, Pattern, UPC, ISBN, EAN, and Google Product Category. Please use these exact names when creating your Option Names in Zen Cart.
Did you name it SIZE or Size?
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