Q: Elgato game capture hd for loepard

Maybe you can't

https://www.elgato.com/en/game-capture-hd-support

System Requirements

• Mac: OS X 10.9 (or later), 4 GB RAM, built-in USB 2.0 port

Realize as a general rule with technology that once any one item in your system gets more than 5 years separated from any other item you are going to run into limitations.

We only know what you tell us. You didn't tell us you knew that so I posted it.