MacOS Big Sur and Apple Silicon / M1 have been supported since V2.9
At least macOS 10.11 El Capitan is needed.
For wireless sync at least iOS 10.13.1 is needed.
To exchange QR-Codes from iOS to macOS a camera is needed.
(Workaround: If your Mac does not have a camera, please create the Safe to synchronize on the Mac first and create the QR code on the Mac. Than capture the QR code with the iOS device).