One suggestion is at the time of uploading files you can create separate folder for individual users inside the target folder. Suppose the target folder name is InitialUploads, then when a user (say User1) tries to upload files, that can be stored inside a folder named User1 inside the Target folder "InitialUploads" and after creating the .zip you can delete this User1 folder.
Please have a look at the following sample code based on the mark-up I provided. When the user login some particular identity for ex. Username will be saved in the session and that you can use while uploading files as follows.
sender, FileUploadedEventArgs e)
targetfolder = AsyncUpload_Attachment.TargetFolder+Convert.ToString(Session[
//Creating user folder if it does not exists in Target folder.
sender, EventArgs e)
uploadTarget = AsyncUpload_Attachment.TargetFolder + Convert.ToString(Session[
startPath = Server.MapPath(uploadTarget);
//source path to create zip files.
zipPath = Path.Combine(Server.MapPath(
//Setting path and filename of .zip to be created.
//creating the .zip
//deleting the user folder in Target folder after creating .zip file