WINDOWS INSTALLATION GUIDE CAN BE FOUND HERE:
GETTING STARTED - Mac Download Installation
Omnisphere 2 is available for download as an installation option for registered users through the Spectrasonics Techshop. Once you have downloaded Omnisphere 2 via the Download Manager, follow this set of instructions to install it on your Mac system.
Note: you'll need over 64GB of free space available on your hard drive in order to continue.
Omnisphere 2 Installation
Step 1: Open the folder 'Omnisphere 2 Installation'
Step 2: Open the Mac folder, then double-click "Omnisphere 2 Installer.pkg" to begin the installation of Omnisphere.
Step 3: Double-click the file "Omnisphere 2 Installer.pkg." The installer might need to quit and re-open to ensure support for older versions of OS X, so just click "OK."
Step 4: Follow the steps as you're guided through the installation process. Make sure to review the Installation Info and Licensing FAQ. Then at the "Destination Select" step, choose the option "Install for all Users of this computer." After the Installation Type information you'll enter your system password to start the install process.
Step 5: The plugin files will then be installed on your Mac's system drive.
Step 6: Then at the Preparation step, you'll select where to install the large core library files. By default they will be installed to your system drive or choose a secondary drive by selecting the button "Choose Location."
Step 7: The large data files will now be copied to your selected drive. Allow for 30-60 minutes to install all of the data.
Step 8: After the installation is complete, select "Close" and now it's time to open up Omnisphere 2 in your host to authorize it.