Unauthorized exception while downloading file from SharePoint

In this article, How to download the SharePoint  library files in Document Library

 var file = clientContext.Web.GetFileByServerRelativeUrl(fileRef);

                clientContext.Load(file);

                clientContext.ExecuteQuery();                    

                ClientResult<Stream> streamResult = file.OpenBinaryStream();

                clientContext.ExecuteQuery();

#sharepoint #SharePoint Developer/  #O365 #Administrator/ #NET #jQuery #AngularJS #poweapps #powerautomate #spfx #pnp #workflo