OpenHab, RSP3 and Audio Out

Hello everybody,
Since a few month openhab does his work at home. Extensions are Homematic , Max Heating, FritzBox And now I would like to have audio issues over Openhab. That’s why I also installed a USB serial adapter, connected speakers and tested it with my little Linux skills. So it works but only on openhab I get no sound output. Where do I have to change or adjust something?
But i am also interested in ideas how you managed it with the audio messages.
Many thanks for your help and sorry for the english, it´s a mixture between school english for about 20 years and google.