C#: How to install System.Web

I am using Visual Studio Code version 1.42 on my Ubuntu 18.04. I just successfully installed sudo dotnet add package Google.Apis.Drive.v3 via terminal but I can't find a way to install System.Web on my C# project.

I tried many different ways:

1) sudo dotnet add package Microsoft.AspNet.WebApi

2) sudo dotnet add package Microsoft.AspNet.Mvc -Version 5.2.7

3) sudo dotnet add package Microsoft.AspNet.Mvc

using Google.Apis.Auth.OAuth2;
using Google.Apis.Download;
using Google.Apis.Drive.v3;
using Google.Apis.Services;
using Google.Apis.Util.Store;

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Web;


//file Upload to the Google Drive.
        public static void FileUpload(HttpPostedFileBase file)
        {
            if (file != null && file.ContentLength > 0)
            {
                DriveService service = GetService();

                string path = Path.Combine(HttpContext.Current.Server.MapPath("~/GoogleDriveFiles"),
                Path.GetFileName(file.FileName));
                file.SaveAs(path);

                var FileMetaData = new Google.Apis.Drive.v3.Data.File();
                FileMetaData.Name = Path.GetFileName(file.FileName);
                FileMetaData.MimeType = MimeMapping.GetMimeMapping(path);

                FilesResource.CreateMediaUpload request;

                using (var stream = new System.IO.FileStream(path, System.IO.FileMode.Open))
                {
                    request = service.Files.Create(FileMetaData, stream, FileMetaData.MimeType);
                    request.Fields = "id";
                    request.Upload();
                }
            }
        }

        //Download file from Google Drive by fileId.
        public static string DownloadGoogleFile(string fileId)
        {
            DriveService service = GetService();

            string FolderPath = System.Web.HttpContext.Current.Server.MapPath("/GoogleDriveFiles/");
            FilesResource.GetRequest request = service.Files.Get(fileId);

            string FileName = request.Execute().Name;
            string FilePath = System.IO.Path.Combine(FolderPath, FileName);

            MemoryStream stream1 = new MemoryStream();

            // Add a handler which will be notified on progress changes.
            // It will notify on each chunk download and when the
            // download is completed or failed.
            request.MediaDownloader.ProgressChanged += (Google.Apis.Download.IDownloadProgress progress) =>
            {
                switch (progress.Status)
                {
                    case DownloadStatus.Downloading:
                        {
                            Console.WriteLine(progress.BytesDownloaded);
                            break;
                        }
                    case DownloadStatus.Completed:
                        {
                            Console.WriteLine("Download complete.");
                            SaveStream(stream1, FilePath);
                            break;
                        }
                    case DownloadStatus.Failed:
                        {
                            Console.WriteLine("Download failed.");
                            break;
                        }
                }
            };
            request.Download(stream1);
            return FilePath;
        }

Post that I consulted to find a solution to this problem were this one, this, also this one. I came across this too which seemed to be related but no luck. Also this last one was useful, however I am confused about which type of package to install.

thanks for providing guidance on how to solve this problem.