Hi @Tom_Goben, welcome to the SharpTools family. 
Yes, you would need either a SmartThings hub or Hunitat hub to connected your zigbee/z-wave devices to SharpTools, and you would want to research a bit if your current smart devices are supported in either of the hub, if you haven’t already.
There are ways to bring wifi-only devices to SharpTools via Alexa (echo). Ex: create the simulated/virtual switches using the SmartThings/Hubitat community developed device handler and use Alexa Routine to sync the state between the device and this simulated/virtual switch which can be shown/controlled in SharpTools.
@josh also posted the details about this approach previously that you might be interested to check.