How to use Access Token in Trustpilot API

Using the Trustpilot API, I was able to request the access and refresh token, but when I try to use them, it doesn't work.

Fetching the Invitation Templates (API Documentation), with the following header, using the access_token value in the Authorization header and the API KEY value for the apikey header:

        [Content-Type] => application/x-www-form-urlencoded
        [Authorization] => Bearer ABCDEFGabcdefg123456123456
        [apikey] => foooooooooooooooooooo123456

I got an HTTP Code 403 with no message in the body, while if I use the refresh_token, I got a 401 code with the following message:

"fault":{"faultstring":"Invalid Access Token","detail":{"errorcode":"keymanagement.service.invalid_access_token"}

As far as I got, I should be able to use the refresh_token too as it should not expire.

From the documentation: Once the access token expires, issue the same request to obtain a new token or use the refresh token obtained in the response.

Any idea of what I am doing wrong?

source https://stackoverflow.com/questions/70868278/how-to-use-access-token-in-trustpilot-api