How to convert Word document to PDF in Azure App service on Linux?

// [C# Code]
private IHostingEnvironment _env;
public HomeController(IHostingEnvironment env)
{
     _env = env;
}
/// <summary>
/// Convert Word document to PDF
/// </summary>
/// <param name="button"></param>
/// <returns></returns>
public IActionResult WordToPDF(string button)
{
     string fileLoadTime = "";
     string domLoadTime = "";
     string conversionTime = "";
     string saveTime = "";
     if (button == null)
        return View("Index");
 
     if (Request.Form.Files != null)
     {
          if (Request.Form.Files.Count == 0)
          {
              ViewBag.Message = string.Format("Browse a Word document and then click the button to convert as a PDF document");
              return View("Index");
          }
          // Gets the extension from file.
         string extension = Path.GetExtension(Request.Form.Files[0].FileName).ToLower();
          // Compares extension with supported extensions.
         if (extension == ".doc" || extension == ".docx" || extension == ".dot" || extension == ".dotx" || extension == ".dotm" || extension == ".docm"
                   || extension == ".xml" || extension == ".rtf")
          {
               MemoryStream stream = new MemoryStream();
               Request.Form.Files[0].CopyTo(stream);
               try
               {
                     //Open using Syncfusion
                     WordDocument document = new WordDocument(stream, Syncfusion.DocIO.FormatType.Automatic);                     
                     stream.Dispose();
                     stream = null;
                     //Hooks the font substitution event
                     document.FontSettings.SubstituteFont += FontSettings_SubstituteFont;
                     // Creates a new instance of DocIORenderer class.
                     DocIORenderer render = new DocIORenderer();
                     // Converts Word document into PDF document.
                     PdfDocument pdf = render.ConvertToPDF(document);
                     //Unhooks the font substitution event after converting to PDF
                     document.FontSettings.SubstituteFont -= FontSettings_SubstituteFont;
                     MemoryStream memoryStream = new MemoryStream();
                     // Save the PDF document
                     pdf.Save(memoryStream);
                     memoryStream.Position = 0;
                     ViewBag.OS = string.Format(System.Environment.OSVersion.ToString());
                     ViewBag.Load = string.Format("FileLoadTime\t" + fileLoadTime);
                     ViewBag.DomLoad = "DomLoadTime\t" + domLoadTime;
                     ViewBag.Conversion = "ConversionTime\t" + conversionTime;
                     ViewBag.Save = "SaveTime\t" + saveTime;
                     return File(memoryStream, "application/pdf", "WordToPDF.pdf");
               }
               catch (Exception ex)
               {
                     ViewBag.Message = ex.ToString();
               }
          }
          else
          {
               ViewBag.Message = string.Format("Please choose Word format document to convert to PDF");
          }
     }
     else
     {
         ViewBag.Message = string.Format("Browse a Word document and then click the button to convert as a PDF document");
     }
     return View("Index");
}
/// <summary>
/// Sets the alternate font when a specified font is not installed in the production environment
/// </summary>
/// <param name="sender"></param>
/// <param name="args"></param>
private void FontSettings_SubstituteFont(object sender, SubstituteFontEventArgs args)
{
      string filePath = string.Empty;
      FileStream fileStream = null;
      //Sets the alternate font when a specified font is not installed in the production environment
      if (args.OriginalFontName == "Calibri")
      {
          filePath = _env.WebRootPath + @"/Fonts/calibri.ttf";
          fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
          args.AlternateFontStream = fileStream;
      }
      else if (args.OriginalFontName == "Arial")
      {
          filePath = _env.WebRootPath + @"/Fonts/arial.ttf";
          fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
          args.AlternateFontStream = fileStream;
      }
      else
      {
          filePath = _env.WebRootPath + @"/Fonts/times.ttf";
          fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
          args.AlternateFontStream = fileStream;
     }
}