I found an article that might help with the FaceTime registration issue you are experiencing on your Mac. I recommend following these steps:
Activating FaceTime for Mac
Use your Apple ID to register and use FaceTime. FaceTime registration validates your Apple ID and email address for use with FaceTime.
If you are unable to activate FaceTime, try the following:
Sign in to FaceTime for Mac using a valid Apple ID. After you validate the email address for use with FaceTime, other FaceTime users can connect to you using that email address. If you encounter issues registering or using an Apple ID account:
- Ensure that you have an active Internet connection.
- Verify that you are using a valid Apple ID at appleid.apple.com. You can also create an Apple ID or reset your password from this website.
- Check that your email address is verified in FaceTime > Preferences.
- If FaceTime > Preferences shows your email status as "verifying," follow the instructions in the verification email that was sent to complete the process.
- Toggle FaceTime off and on in FaceTime > Preferences.
- If still unable to Sign In follow the instructions in FaceTime, Game Center, Messages on OS X: Troubleshooting Sign in
You can find the full article here:
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