ForNAV direct print with client print will generate and download a file with the fornavprint file name extension. On a computer that hasn't used client print before, the downloaded print job will be saved in the default download folder for the user.
If you want it to open automatically so the user doesn't have to press any keys or use the mouse, you can tell your browser to open files of this type automatically. To do this, right-click the file when the browser shows it is downloaded and select Always open files of this type.