Hey,
Unfortunately the Slab Component seems not to be able to create slabs with holes - however there is the possibility to reshape (cut) your slabs. However therefore you need to get the cut polygon (= the inner boundary curve) from your Zone.
If you want to apply your script on a list of many different zones and all of them are different I would recommend you to be familiar and comfortable with Data Trees and how List Management in Grasshopper is working.
Moreover in the current version of the AC23 Grasshopper Connection the Reshaping Component, as well as influencing what geometry is sent and synchronized with AC is a bit buggy - you may encounter crashes and lack of satisfaction.
