If you are from Germany, just follow the steps without using a proxy.
Now ... if you are from anywhere else you will need to use a manual proxy.
To receive the dress you need to click where it says "Besuche die offizielle webseitte, um eins dieser tollen Violetta-Outfits zy erhalten" and you will be redirected to the official Germany Violetta site. you can close the window.
special thanks to MissMeryLu2000m