Reference 4 requirements
PC: Windows 7 or later (32 & 64 bit)
Mac: macOS 10.12 Sierra or later
Starting from Reference 4.3, the Systemwide app is fully supported on macOS 10.12 Sierra or later. This is because starting from macOS 10.12, the OS allows setting an external audio clocking which improves audio signal sync between virtual and physical audio devices.
Reference Measure app and the DAW plugin are also taking advantage of some features only available starting from macOS 10.12, so it is not possible to run newer of those modules separately on 10.11 or lower. All software modules require macOS 10.12 or higher to run with the supported versions.
Reference 4.4 is also fully supported on macOS 10.15 Catalina.