If you open the Notifications add-on inside your Google Forms and the program instantly crashes with an error message saying
drive.google.com refused connection, the fix is simple.
Google Forms add-ons may sometimes display an error, or crash with a sad face, when multiple Google accounts are authorized in the same browser session.
To resolve the issue, go the File menu in Chrome and choose New Incognito Window. Open the same Google Form in Chrome's incognito mode and launch the add-on again.
Alternatively, you may sign out of multiple Google accounts and only sign-in with the account that owns the Google Form.