Create an envelope using Composite template.

CompositeTemplateSample.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DocuSign.eSign.Api;
using DocuSign.eSign.Client;
using DocuSign.eSign.Model;
using Newtonsoft.Json;

namespace DocuSignRecipe
{
    public class TestCompositeTemplates : DocuSignApiBase
    {
        public void CreateEnvelopeFromCompositeTemplate()
        {

            string accountId = Init();


            var envDef = new EnvelopeDefinition()
            {
                EmailSubject = "Envelope with multiple documents",
                Status = "sent",
                CompositeTemplates = new List<CompositeTemplate>()
            };

            string serverTemplateId = "";//Add your Server TemplateId here.
            for (int docNumber = 1; docNumber <= 3; docNumber++)
            {
                envDef.CompositeTemplates.Add(new CompositeTemplate()
                {
                    ServerTemplates = new List<ServerTemplate>()
                    {
                        new ServerTemplate()
                        {
                            TemplateId = serverTemplateId,
                            Sequence = docNumber.ToString()
                        }
                    },
                    InlineTemplates = new List<InlineTemplate>()
                    {
                        new InlineTemplate()
                        {
                            Sequence = docNumber.ToString(),
                            Recipients = new Recipients()
                            {
                                Signers = new List<Signer>()
                                {
                                    new Signer()
                                    {
                                        Email = "Janedoe@acme.com",
                                        Name = "Jane Doe",
                                        RecipientId = "1",
                                        RoleName = "Signer1",
                                        Tabs = new Tabs()
                                        {
                                            TextTabs = new List<Text>()
                                            {
                                                new Text()
                                                {
                                                    DocumentId = docNumber.ToString(),
                                                    PageNumber = "1",
                                                    XPosition = "100",
                                                    YPosition = "100",
                                                    Width = 120, 
                                                    Value = "Some Tab Value " + docNumber.ToString()
                                                }
                                            }
                                            
                                        }
                                    }
                                }
                            }
                        }
                    }
                });

            }

            EnvelopesApi envelopesApi = new EnvelopesApi();
            EnvelopeSummary envelopeSummary = envelopesApi.CreateEnvelope(accountId, envDef);
            Console.WriteLine(envelopeSummary);

        }
    }
    
    public class DocuSignApiBase
    {
        protected const string _username = "";//Add your UserName here
        protected const string _integratorKey = ""; //Add your integrator key here.
        protected const string _password = ""; //Add your account password here.
        protected const string _baseUri = "https://demo.docusign.net/restapi";

        protected string _authHeader;

        public DocuSignApiBase()
        {
            // configure 'X-DocuSign-Authentication' header
            _authHeader = "{\"Username\":\"" + _username + "\", \"Password\":\"" + _password + "\", \"IntegratorKey\":\"" + _integratorKey + "\"}";

        }

        public string Init()
        {
            // initialize client for desired environment (for production change to www)
            ApiClient apiClient = new ApiClient(_baseUri);
            Configuration.Default.ApiClient = apiClient;


            Configuration.Default.AddDefaultHeader("X-DocuSign-Authentication", _authHeader);

            // we will retrieve this from the login API call
            string accountId = null;

            /////////////////////////////////////////////////////////////////
            // STEP 1: LOGIN API        
            /////////////////////////////////////////////////////////////////

            // login call is available in the authentication api 
            AuthenticationApi authApi = new AuthenticationApi();
            LoginInformation loginInfo = authApi.Login();

            // parse the first account ID that is returned (user might belong to multiple accounts)
            accountId = loginInfo.LoginAccounts[0].AccountId;

            // Update ApiClient with the new base url from login call
            apiClient = new ApiClient(loginInfo.LoginAccounts[0].BaseUrl);

            return accountId;
        }
    }
}