This article assumes you have a Guarded ID license. For an alternate method, check the article "How can I install the extension without GuardedID?"
If you have GuardedID, right click on the "G" in the notification area. Then, choose "Check for Updates". Click on the popup that reads "GuardedID Cryptocolor is Available". It should state that it is asking you to install NoClickjack for Google Chrome.
(Windows 10 Example)
You should be redirected to the Google Play Store. Click the blue "Add to Chrome" button in the top right of the extension window, then choose "Add Extension" when the window prompts you to.