API Authentication with Meta token


I have a developer account on Meta with registered WhatsApp templates which is all working. I can send template message requests via bubble to Meta without a problem when the Authorization is added as a header in the call.

I want to specify the Authorization and token on API level for when I have multiple calls, when it changes I can change one item and do not have to change for each call.
But I do not know which Authentication to use. I’ve tried ‘Private key in header’ without any success.

and I’ve tried ‘0Auth2 Custom Token’ without any success.

Each time I get a generic error message 400 stating the messaging_product is incorrect. (Which is not the case since it works when Authorization is added on the call level)