Api.box.com : Error "Grant credentials are invalid"

I created personal Box account and am attempting to request a token using the client ID and secret. I am getting the following error.

{“error”:“invalid_grant”,“error_description”:“Grant credentials are invalid”}

Here are my application settings and requests:

App access level : App + Enterprise access
Authentication method: Server Authentication (Client Credentials Grant)

curl -X POST https://api.box.com/oauth2/token
-d “grant_type=client_credentials”
-d “client_id=redacted”
-d “client_secret=redacted”
-d “box_subject_type=user”
-d “box_subject_id=redacted”

I am providing the user_id of my Box account as the box_subject_id.