How to add files using file URLs when sending a document for eSignature?

curl -X 'POST' \
  'https://api.boldsign.com/v1/document/send' \
  -H 'accept: application/json' \
  -H 'X-API-KEY:{Your API Key}' \
  -H 'Content-Type: application/json' \
  -d '{
    "Message": "Please sign this.",
    "Signers": [
        {
            "name": "Alex",
            "emailAddress": "alexgayle@cubeflakes.com",
            "signerType": "Signer",
            "formFields": [
                {
                    "id": "sign1",
                    "name": "sign1",
                    "fieldType": "Signature",
                    "pageNumber": 1,
                    "bounds": {
                        "x": 50,
                        "y": 50,
                        "width": 125,
                        "height": 25
                    },
                    "isRequired": true
                }
              ],
            "locale": "EN"
        }
    ],

   "FileUrls": [
        "https://www.dropbox.com/scl/fi/jcya44l0ui2sq4rjl0wsg/Customer-Contract-Form-Cubeflex.pdf?rlkey=earhpfci3i2zqzugcchxkb451&st=sjbm7jcs&dl=1"
    ],
   
    "Title": "Customer-Contract-Form-Cubeflex"
  }'
  

using BoldSign.Api;
using BoldSign.Model;

var apiClient = new ApiClient("https://api.boldsign.com", "{Your API Key}");
var documentClient = new DocumentClient(apiClient);

var signatureField = new FormField(
    id: "sign",
    isRequired: true,
    type:FieldType.Signature,
    pageNumber: 1,
    bounds: new Rectangle(x: 100, y: 100, width: 100, height: 50));

var formFieldCollections = new List<FormField>()
{
    signatureField
};

var signer = new DocumentSigner(
    signerName: "Alex",
    signerType: SignerType.Signer,
    signerEmail: "alexgayle@cubeflakes.com",
    formFields: formFieldCollections,
    locale: Locales.EN);

var documentSigners = new List<DocumentSigner>()
{
    signer
};
List<Uri> uriList = new List<Uri>
{
    new Uri("https://www.dropbox.com/scl/fi/v5vj574fdb1zgkawgud8p/FL-Landlord-and-Tenant-Law-Problem.pdf?rlkey=68e21wfenuyqvolr4jl07yt8p&st=k8ryipoe&dl=1")
};
var sendForSign = new SendForSign()
{
    Message = "Please sign this",
    Title = "Agreement",
    HideDocumentId = false,
    Signers = documentSigners, 
     =  uriList
   

};
var documentCreated = documentClient.SendDocument(sendForSign);
Console.WriteLine(documentCreated);

import requests
import json

url = "https://api.boldsign.com/v1/document/send"

signer_data = {
    "name": "Alex",
    "emailAddress": "alexgayle@cubeflakes.com",
    "signerType": "Signer",
    "formFields": [
        {
            "id": "sign1",
            "name": "sign1",
            "fieldType": "Signature",
            "pageNumber": 1,
            "bounds": {
                "x": 50,
                "y": 50,
                "width": 200,
                "height": 25
            },
            "isRequired": True
        }
       
    ],
    "locale": "EN"
}

payload = {
    'Message': 'Please sign this.',
    'Signers': [signer_data],
    'Title': 'Agreement',
    'FileUrls': [
        'https://www.dropbox.com/scl/fi/jcya44l0ui2sq4rjl0wsg/Customer-Contract-Form-Cubeflex.pdf?rlkey=earhpfci3i2zqzugcchxkb451&st=sjbm7jcs&dl=1'
    ]   
}

headers = {
  'Content-Type': 'application/json',
  'accept': 'application/json',
  'X-API-KEY': '{Your API Key}'
}

response = requests.post(url, headers=headers, json=payload)
print(response.text)

const axios = require('axios');

const url = "https://api.boldsign.com/v1/document/send";

const signerData = {
  "name": "Alex",
  "emailAddress": "alexgayle@cubeflakes.com",
  "signerType": "Signer",
  "formFields": [
    {
      "id": "string",
      "name": "string",
      "fieldType": "Signature",
      "pageNumber": 1,
      "bounds": {
        "x": 50,
        "y": 50,
        "width": 200,
        "height": 25
      },
      "isRequired": true
    }
  ],
  "locale": "EN"
};

const payload = {
  'Message': 'Please sign this.',
  'Signers': [signerData],
  'Title': 'Agreement',
  'FileUrls': [
    'https://www.dropbox.com/scl/fi/jcya44l0ui2sq4rjl0wsg/Customer-Contract-Form-Cubeflex.pdf?rlkey=earhpfci3i2zqzugcchxkb451&st=sjbm7jcs&dl=1'
  ]
};

const headers = {
  'Content-Type': 'application/json',
  'accept': 'application/json',
  'X-API-KEY': '{Your API Key}'
};

axios.post(url, payload, { headers })
  .then(response => {
    console.log(response.data);
  })
  .catch(error => {
    console.error('Error:', error);
  });