Gettin a "Forbidden" error message when pretanslating a document

Hello

We are currently experiencing the following problem. A "Forbidden" error message pops up every time we want to run the "pre-translate" function. The rest of the project creating is working smoothly. However, this error message doesn't allow us to work with DeepL and finally Post Editing tasks remain impossible to do. 

DeepL reported back to us that this error message does not come from their end.

If it helps: we use the lates Trados Studio version.

THANK YOU so much for your support.