It was a sales rep that told me that and their documentation implies I still need an on-prem device, just not sure why.
“This easy to use web application controls user permissions and license management. The SmartOffice Manager is available in a standalone appliance platform which connects directly to your local network and communicates with your cloud-based or on-premise Sangoma phone system for user directory information. It is also optionally available as a software module for on-premise FreePBX/PBXact customers”