How to install zbrush for mac 3.12 .
You cant opend the application “Zbrushosx” becasue
it is not supported on this architecture ?
My mac system is 10.5.5
Thanks all . 
What you should have downloaded is a .dmg file. Double-click that file to mount it. This will then open a window that shows the ZBrush icon on the left and your Apps folder on the right. Drag the ZBrush icon onto the Apps folder to install ZBrush. Then unmount the image.
Now go to your Apps folder and run ZBrush from within it.
If you continue to have difficulty, please contact [email protected]. Include detailed information about your system and your issue, and also be sure to include your purchase info.