Is there a free download trial for MAC version of SigmaStat?
No, there is no version of SigmaStat compatible with mac because it was discontinued and its features were embedded into the new application called SigmaPlot. You can check this information on the official website. According to the system requirements, not even SigmaPlot is compatible with Mac. In this case, the only thing you can do is to install one of the supported Windows versions on your Mac through Bootcamp.