There are some reasons for authorization error.
If you have 2 factor authentication or captcha turned on for your GTalk account, you’ll need to create an application specific password to use with the app.
If the above does not apply to you, and you’re certain that you entered your username and password correctly, you may want to check Google’s client verification.
Or maybe you turned off Hangouts service in the Google Admin console.
Please check the links below.