Mari 4.0v1 will not be released with a Mac OS X build available for download. Mari 4.0v1 will instead only be available for artists using Windows and Linux based operating systems.
During the development stages of Mari 4.0v1, Mari was updated to use the QT 5 UI libraries as part of the efforts to support the VFX Reference Platform 2017. Due to the nature of the QT libraries which are not created by Apple, we have found that building a Mari 4.0 Mac OS X version required more development time in order to ensure we offer the same quality user experience, as for the other operating systems.
With this in mind, we have chosen to advance with Mari 4.0v1 for Windows and Linux customers only, and continue working on the Mac OS X release with the aim to make it available in a future version.
We want to make sure that everyone's experience with Mari 4.0 is great from the first version onward. Both Foundry and Apple feel that a quality user experience is important and worth the extra development time this will involve.