Why is my API GET request failing to authenticate?

I’m trying to set up a GET request to an API that authenticates using a JSON Web Token (JWT).

I’ve successfully got the token, by storing the credentials in Secrets in my Knime Hub profile, and using the Secrets Retriever.

The API I’m trying to call is this one, and I’m hitting the error on step 6: Blackbaud

I’ve fed the token in via the Credential input port. I’ve also added my subscription key into the header fields as instructed.

I can’t see a way to input the token into the header, but from reading around the topic, it seems that should be handled automatically by the tool.

But my GET request is returning a 403 Forbidden error. I’ve tried refreshing the tokens but I still get the error. Is there a way I can get more info on why it is failing? Or can anyone spot what is going wrong?