Launch your version of TIA Portal (V14 or newer). Retrieve the Project: Do not use File > Open , as this will fail for .zap14 files. Select Project > Retrieve from the top menu. Navigate to your downloaded file and select it.

Unlike standard project files, these archives must be "retrieved" rather than simply opened.

Save the .zap14 file from your source (email attachment or cloud storage) to a known location like your Downloads folder or desktop.