If the PDF you downloaded isn't showing up in your file manager, try checking your Downloads folder first. On Android, open the Files or Downloads app and look for the file there. On Windows, check the Downloads folder in File Explorer, and on macOS, open Finder and go to the Downloads section. If you still can't find it, the download location might have been changed in your browser settings, so you can check there. Alternatively, try searching for the file by name or check the recently opened files in your browser or file manager.