Deepl Pro - "Forbidden!"?

Hi together,

I just baught a DeepL Pro subscription and downloaded the plugin for Trados Studio 2017. I had a subscription a while back and made sure to uninstall the old version of the plugin first to avoid conflicts. Upon opening Studio 2017, it never asked me for the authentication key. When I try to translate a document now, I get the charming message "Forbidden". Can anybody help please? Thank you! 
Best wishes and stay healthy,