Zello For Work only supports the SiteCAST from CriticalRF.
However, Zello will work with most existing PC-Radio interfaces, including those intended for Echolink and other RoIP applications. It supports three types of radio control (both ways): VOX, COM(RS232) and CM108-based devices (coming soon).
Other hardware that should work with Zello For Work is any echolink-compatible interface.
Some manufacturers offer ready-to-use cables to connect to your radio. Others don't, and you may have to build or order the cable separately.