Esign：使用v6 api PHP将签名块定位到特定位置

I have tried changing the postion of default signature added by adobe esign at the end of document. I have tried using

" 'contentType' => 'SIGNATURE_BLOCK'    " 

in fields property for the api : api/rest/v6/agreements/{agreementId}/formFields . But it doesn't work with "SIGNATURE_BLOCK" contentType and field is not shown in pdf in required location.

So adding "contentType" parameter with any value 'SIGNATURE_BLOCK' or 'SIGNATURE' or 'SIGNER_NAME' or 'SIGNER_FIRST_NAME' or 'SIGNER_LAST_NAME' or 'SIGNER_INITIALS' or 'SIGNER_EMAIL' doesn't add fields to document.

Here is link from adobe https://helpx.adobe.com/sign/kb/formfields-option-is-not-available-in-v6-of-rest-api-adobe-sign.html , i have used as reference.

Please Help , how to use the api appropriately .

Here is the PHP array i have used :
             ['fields' =>
                    [
                        [
                            'locations' =>
                            [
                                [
                                    'pageNumber' => 1,
                                    'top' => 600,
                                    'left' => 300,
                                    'width' => 111,
                                    'height' => 30,
                                ]
                            ],
                            'name' => 'test_es_:signer:signature',
                            'inputType' => 'SIGNATURE',
                            'recipientIndex' => 1,
                            'alignment' => 'RIGHT',
                            "required" => 1,
                            'contentType' => 'SIGNATURE_BLOCK'
                        ],

                    ]
             ]

Thanks