The Free Shipping freeshipper shipping module is triggered by 0 weight and Always Free Shipping orders ... and is for Everyone, meaning that all Zones get Free Shipping when this is triggered ...

NOTE: the Zone setting is included for advanced coders for ease of use in customizations ...


The Free Shipping Options freeoptions shipping module is triggered by settings on the Total, Item Count or Weight ...


The Order Totals ... Shipping ot_shipping ... Free Shipping on orders over XX.XX amount does not use a shipping module to manage this ...


Currently, I did not get Free Shipping of any kind when I added $100.00 worth of products to the cart so I am not sure your current settings or if you have a Zone set on the Order Totals module Shipping ot_shipping or if you have turned it off ...

NOTE: you have a really old version of Zen Cart and should really consider upgrading soon ...