The Universal Extensions are available in the Chrome web store for download and can be pushed out through the console to users under Chrome management or out to Chrome devices "Chromebooks".
Log into the Google Admin console.
Go to Device Management > Chrome > User Settings
Scroll down to the Chrome Web Store section and select Manage for "Recommended Apps and Extensions".
Select the Chrome Web Store and search for and select the extensions that you want to add to the user's profile. See Chrome for education Help
*You can also Force-install the Apps and Extensions so users can not remove or tamper with them. See How to force-install