Please help with Domain verification via API request

Hello! Even I am trying to verify the domain, via Postman request, i got facing this error:

"statusMessage": "Payment Services Exception Domain check failed with the following errors. No domains were registered.\nDomain verification failed for pspId=*** domain=***.io url=/.well-known/apple-developer-merchantid-domain-association errorMessage=Failed to pull domain file statusCode=403",
    "statusCode": "400"

I am use this body to make POST request:

{
    "domainNames": [
        "***.io"
    ],
    "encryptTo": "***",
    "partnerInternalMerchantIdentifier": "***",
    "partnerMerchantName": "***"
}

What can be wrong here?