There are a lot of different reasons that you might run into this error.
You, and thus, your token do not have access to the resource
Your token doesn’t have the correct scopes to access the resource
Without sharing your actual developer token, can you maybe share a screenshot of the API request you’re making (showing the Authorization header, but mangling or redacting the developer token)?
Could you also share a screenshot of the scopes you’re setting for the token?