Some users have had problems with the update manager, if that's the case, please download the latest version directly from rekordbox.com and run the installer. It will install over the existing version and nothing will change in your database.
As for the audio output, please ensure that you have the drivers correctly installed BEFORE connecting it to your computer (consider downloading the drivers again from the website, run the uninstaller then install anew). Next, once rekordbox is open, check that you have the device configured within your audio preferences.