Thanks for reaching out. If you want to set up the Chromecast Voice Remote buttons and control your soundbar but, the brand of your soundbar isn't on the list of supported device brands for the Chromecast with Google TV (HD) and Chromecast Voice Remote, it means that it is not compatible.
As a workaround, you may try to choose a different brand from the list, which in your view has the same country of manufacture as the soundbar. You may also search for soundbar remote codes online and see if any other brand matches the same code as Blaupunkt, and select that other brand instead. However, please be informed that this step may or may not work.