Please refer this wiki topic to enroll MAC OS X devices to ITSM portal.
Step : Go to IT and Security Manager → Chose Device List from the left side pane and click Enroll device button.
Step : Once you click the button it will display the logged in c1 account information for enrollment on that select show enrollment instructions and select For Apple devices.
Step : After downloading the file in a portal, click the downloaded file it will follow the instructions for enrollment of Comodo Client Communication in Mac System on that click "Continue" Button.
Step : Click "Continue" Button for agreeing on the end user license agreement.
Step : After Clicking the License Agreement click the "Agree" Button for installing the application in your device.
Step : If you change Install Location it will redirect you to save the path of the file where the file you are going to save in the destination.On that click "Continue" Button.
Step : After changing the location click "Install" Button on the screen.
Step : Then installation followed by providing the credentials for your machine on that click "Install software".The application will be successfully installed in your account.