Fedex Shipping method throwing error

-- url of the page with the problem -- : conantacres.com/index.php/our-store
-- HikaShop version -- : 5.1.5
-- Joomla version -- : 5.2.5
-- PHP version -- : 8.3.19
-- Browser(s) name and version -- : chrome
-- Error-message(debug-mod must be tuned on) -- : Client error: `POST apis.fedex.com/oauth/token ` resulted in a `401 Unauthorized` response: {"transactionId": "cda8adc0-0ecc-43c5-a04a-25439fb1bf66","errors":[{"code":"NOT.AUTHORIZED.ERROR","message":"The given c (truncated...)

We've checked and rechecked the Id's and APIs on the fedex account, but are still getting this error.

Client error: `POST apis.fedex.com/oauth/token ` resulted in a `401 Unauthorized` response: {"transactionId": "cda8adc0-0ecc-43c5-a04a-25439fb1bf66","errors":[{"code":"NOT.AUTHORIZED.ERROR","message":"The given c (truncated...)

Any ideas?

Client made a correction to the secret key, but getting a different error now:

FORBIDDEN.ERROR
We could not authorize your credentials. Please check your permissions and try again.

Is this a response from Fedex?