invalid_grant

Hi,

I'm getting below errors while creating the access token in postman.

where I'm using grant type(authentication) as client _credentials

and I'm passing the below json in the body

if I pass below json body

{
    "grant_type" : "client_credentials",
    "client_id" : "h84vbkfecpv28scfvj4fxnddf7fh506m",
    "client_secret" : "Oh5mYwWMhWKPDc9O9a2IasmCujQkrEhv"

}

then I'm getting this error : {"error":"unauthorized_client","error_description":"The \"box_subject_type\" value is unauthorized for this client_id"}

ANd if I pass blow json 

{
    "grant_type" : "client_credentials",
    "client_id" : "h84vbkfecpv28scfvj4fxnddf7fh506m",
    "client_secret" : "Oh5mYwWMhWKPDc9O9a2IasmCujQkrEhv",
    "box_subject_id": "25026242758",
    "box_subject_type": "user"
}

then I'm getting this error : {"error":"invalid_grant","error_description":"Grant credentials are invalid"}

I've used app access only and using individual account 

please help me to find solution.