After you have installed the Google Forms add-on, it can be accessed and launched from any Google Form that is associated with your Google account.
forms.google.com and open any existing Google Form in your Drive. Or you can type
forms.new in your browser's address bar to create a new form where you wish to use the email addon.
Inside the Form editor, click the
Add-ons icon that resembles a puzzle piece as shown in the screenshot. Nex, choose
Email Notifications for Google Forms from the list of available add-ons. If you are running the add-on for the first time inside a Google Form, you may also have to choose
Enable Notifications to activate the add-on form for that Google Form.