Get sub-account's Futures account balance using KuCoin API and Google Apps Script

I am trying to get a value (USDT) from KuCoin sub-account's Futures account but having an issue. Here is the script:

function getKuCoinBalance(apiKey, secretKey, passphrase, asset) {
    var endpoint = "/api/v1/accounts";
    var baseUrl = "https://api.kucoin.com";
    var timestamp = Date.now().toString();
    var method = "GET";

    var strForSign = timestamp + method + endpoint;
    var signature = Utilities.computeHmacSignature(Utilities.MacAlgorithm.HMAC_SHA_256, strForSign, secretKey);
    var encodedSignature = Utilities.base64Encode(signature);

    var passphraseHash = Utilities.computeHmacSignature(Utilities.MacAlgorithm.HMAC_SHA_256, passphrase, secretKey);
    var encodedPassphrase = Utilities.base64Encode(passphraseHash);
 
    var options = {
        'method' : method,
        'headers' : {
            'KC-API-SIGN' : encodedSignature,
            'KC-API-TIMESTAMP' : timestamp,
            'KC-API-KEY' : apiKey,
            'KC-API-PASSPHRASE' : encodedPassphrase,
            'KC-API-KEY-VERSION' : '2'
        }
    };

    var url = baseUrl + endpoint;
    var response = UrlFetchApp.fetch(url, options);
    Logger.log(response)
    var dataAll = JSON.parse(response.getContentText());
    var data = dataAll.data;

    for (var i = 0; i < data.length; i++) {
        if (data[i].currency == asset) {
            return data[i].balance;
        }
    }
}

I am able to get data of different types of accounts (trade, isolated, main), you can find the API information Here, but I am looking to get sub-account's Futures account details, as shown in the following image:

I believe I am making a mistake in using the correct URL, I reckon the correct url can be /api/v1/account-overview?currency=USDT but it throws the following error:

Exception: Request failed for https://api.kucoin.com returned code 404. Truncated server response: {"code":"404","msg":"Not Found","retry":false,"success":false} (use muteHttpExceptions option to examine full response)

Can you please guide me in the right direction? Any help would be much appreciated.

On looking the API Information that you provided in your question, I found this endpoint that can be used to get the balance of any sub-account. So here is the workflow:

1. First, get the user id of your sub-account by using this request: /api/v1/sub-accounts

2. Then use this user id in your code. So the modified script would be:

Script Code:

 function getKuCoinSubAccountFuturesBalance(apiKey, secretKey, passphrase, currency) {
  var endpoint = "/api/v1/account-overview";
  var baseUrl = "https://api-futures.kucoin.com";
  var timestamp = Date.now().toString();
  var method = "GET";

  var strForSign = timestamp + method + endpoint +"?currency="+currency;
  var signature = Utilities.computeHmacSignature(Utilities.MacAlgorithm.HMAC_SHA_256, strForSign, secretKey);
  var encodedSignature = Utilities.base64Encode(signature);

  var passphraseHash = Utilities.computeHmacSignature(Utilities.MacAlgorithm.HMAC_SHA_256, passphrase, secretKey);
  var encodedPassphrase = Utilities.base64Encode(passphraseHash);

  var options = {
    method: method,
    headers: {
      'KC-API-SIGN': encodedSignature,
      'KC-API-TIMESTAMP': timestamp,
      'KC-API-KEY': apiKey,
      'KC-API-PASSPHRASE': encodedPassphrase,
      'KC-API-KEY-VERSION': '2'
    },
    muteHttpExceptions: true
  };

  var url = baseUrl + endpoint +"?currency="+currency;
  var response = UrlFetchApp.fetch(url, options);
  var dataAll = JSON.parse(response.getContentText());
  return dataAll.data.accountEquity;
}

Note: Use Sub Account credentials (API and Secret key)

Let me know if it helps.