The Rocket Beans TV Half Marathon badge is regional, not available globally. Not sure whether in Germany only, or elsewhere. When you log into your account at the address https://www.garmin.com/account/profile/, what Location are you registered at, there?
Change your location on https://www.garmin.com/account/profile/ temporarily to Germany, log out from Garmin Connect web, log in back again, open your half-marathon activity, click Edit, then save, and you'll get your badge. Then you can set your location back to Austria, the badge will stay (unless you edit the activity again).
