If you use a Security Key to sign in to G Suite
If you use a Security Key to sign in to G Suite, you should go to chat.google.com in a web browser to use Hangouts Chat. Don't use the Hangouts Chat native apps for Windows or macOS, because the Security Key is not compatible with those apps.
Note: If your domain supports sign-in methods other than Security Key, you may be able to use the native apps. To try this, when you sign in, click Having trouble? and pick a method other than Security Key. If you don't see Having trouble? when you sign in, this method isn't available on your domain, and you should use chat.google.com.