Is there any thing wrong with my setting to activate DeepL add-on?

I followed this article to set our DeepL add-on.


But it always shows the error below.

"This secret field has an invalid value in the saved configuration."
Follow the api 400 error, it shows "This account is not allowed to access the API."
Our DeepL account is registed a week ago, still under the free trail (a month free).
Is it our Account's problem? Or we missed something else?

Looking for your reply.
emoji