I’m not a mac user but I was wondering if you followed the instructions exactly as stated?
Using the Steinberg Application Installer Tool:
Installation from DVD: Insert the DVD. It will be automatically mounted by Mac OS X, which means being made accessible in a new window.
Installation using a downloaded medium (*.dmg or *.iso): Double-click the downloaded image file to mount it, which means opening it as a virtual drive in a new window.
Leave the window as it is. Do not start the installation!
Instead, download the Steinberg Application Installer Tool.
After the download has been completed, double-click on the downloaded file Steinberg_Application_Installer_Tool.dmg.
A new window opens. Inside, double-click on the ‘Steinberg Application Installer Tool.app’ to start the utility.
If the tool recognises the already mounted installer, the installation will be suggested within a newly opened dialog box.
Click on [OK] to start the installation.
If no compatible installer can be found, an error message pops up. In case an installer is not being recognised even though it is listed below, please contact our support team via your MySteinberg account.