Please provide some more detail on this problem, do you have a laptop with Bang & Olufsen audio or are you trying to connect to an external Bang & Olufsen device?
If your laptop came with Bang & Olufsen audio, then to get the app, you need to go to the support page for your laptop on the manufacturers website, they should provide the OEM app to download form there.
If you have any difficulty locating that support page, click your Start Button, then just type msinfo and press Enter, please provide a screenshot of the resulting System Information window.