Your assumption is wrong : the SmartThings Hub supports only Z-wave devices for which a SmartThings specific device handler has been developed.
According to this list of ST compatible devices, FGS-221 is definitely NOT officially supported at this time.
Furthermore, you would need a US version of the FGS-221 (908,4 MHz).
Look at this Fibaro Things - General thread for advanced Fibaro Devices Custom Handlers… and all the caveats which come with them.