Garmin Express (on Mac) won't login into my account

Hello,

I cannot login into my Garmin Account with Garmin Express, which I need to upload Music onto my watch. Procedure:

1. Log-In with e-mail and passwort
2. Getting security code
3. Entering security code
4. Getting following error message: 
5. Click "Wiederholen" doesn't help.

So I am typing here parallel and I am able to login on Website I assume the servers are alive and reachable....