If you are running the app in the mendix cloud this is not a feature that can be implemented directly as you have no access from that environment to a shared drive. Then you’ll need to do something with ftp functions to upload the file to an FTP directory e.g.

If the app is running in another environment for which you have control over the access then you can create a java action that can store the file in a shared drive. For the implementation just google on storing a file from an inputstream in java, as you can get the content of the file from the Core.GetFileDocumentContent method.