Unable to create customers with API

[Darshan Dhabale]

Hi google ads team,
I am trying to create a customer on my manager account, but the API is 
throwing error, here are the details of the request, followed by response.
curl --location 
'https://googleads.googleapis.com/v17/customers/3263459376:createCustomerClient'
 
\
--header 'developer-token: hN6dsqjNmj3tWdITcPd_Qg' \
--header 'login-customer-id: 3263459376' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer 
ya29.a0AcM612ysmnJ9LaZv795YB5_2U9oswds2F50hK2WeM8SdHJlpt3Q4-Bw9_yRioGdI0-9O1UqAkDkDeiSPl501z8zJaRpgLApTrw1dquvjy9VGLNs4Spsjh3PZg3znuRZLXZDEbWcCMUuDvhIh2KMaBQ7iR_qmcBCA4YSXaCgYKASESARMSFQHGX2MiIJxuU5MWTzMel1DCd89RQg0171'
 
\
--data-raw '{
    "customerClient": {
        "descriptiveName": "Sample User"
    },
    "accessRole": "STANDARD",
    "validateOnly": true,
    "emailAddress": "u...@gmail.com"
}'

and here is the response
{
    "error": {
        "code": 400,
        "message": "Request contains an invalid argument.",
        "status": "INVALID_ARGUMENT",
        "details": [
            {
                "@type": 
"type.googleapis.com/google.ads.googleads.v17.errors.GoogleAdsFailure",
                "errors": [
                    {
                        "errorCode": {
                            "notAllowlistedError": 
"CUSTOMER_NOT_ALLOWLISTED_FOR_THIS_FEATURE"
                        },
                        "message": "Customer is not allowlisted for 
accessing this feature."
                    }
                ],
                "requestId": "r_-ko7wXWGALgTyP514hhw"
            }
        ]
    }
}

Thanks for your support

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