JBL 3.1 Soundbar cutting out PCM

So the seller of this house I just purchased left his tv and JBL soundbar behind. I’m using it for the first time on Apple TV and the sound keeps cutting out and the soundbar will say “PCM”. I’ve googled around and went to check the connections and noticed the soundbar isn’t connected to tv with hdmi, only power cord and optical. Do I need to connect an HDMI between the sound bar and tv as well or would there be a separate issue since evidently it can’t be a bad hdmi connection?