KASTA does not require a hub or bridge to operate.
If you want to have remote control outside your house or you want to use voice control, you should add a KASTA-CCGW Cloud Connect Gateway into your KASTA mesh network. If you want to control KASTA from another platform such as Control4, Crestron, RTI, you should add a KASTA-PGW Plexy Gateway into your KASTA mesh network.