Invalid client identifier {0} when trying oauth2/token

API Platform
,
1

Hello. I’m starting the POC work and is trying on the oauth/token for the token. The aim is to try API Retrieve referral worklist (A008, FHIR STU3)

I created sandbox/dev/int environment in the developer account and tried. But all returns the error of

{

"fault": {

    "faultstring": "Invalid client identifier {0}",

    "detail": {

        "errorcode": "oauth.v2.InvalidClientIdentifier"

    }

}

}

I’d like to ask if this is something to do with the onboarding or is there anything I missed? Thank you so much.