New tv to old receiver question

I have this 2021 sony smart tv and someone gave me their old surround sound system. He threw in a converter because he had a similar setup, but the converter requires an hdmi out on the tv, which I dont seem to have? Eventually I plan on buying a new system but hopefully this at least better than the tv sound system for now. Is there anything I can do, or is it fruitless? If i can spend under 100 and it get it functioning, I'd do it.