Download Hidden for OS X from your tracking control panel (the download link is at the bottom of the page).
Locate the Hidden.zip file in your Downloads folder and extract it (this is usually as simple as double-clicking on the .zip file).
Run the extracted Hidden.pkg file by double-clicking on it. This will launch the installer.
Once complete, you will be prompted with a registration pop-up dialog box. Enter your hiddenapp.com username and password and click ‘Register computer’.
Your device is now protected and should be visible in your Tracking Control Panel.
Now you should follow the OS X post-installation protection steps you can read by clicking here.