TV Audio to Wireless Headphones

Hello everyone. I am having an issue setting up a wireless connection from my brand new Hysense 40 inch smart TV to my wireless headphones. I have hearing issues and want to use the headphones to listen to TV. The TV has a HDMI (ARC) which is the only audio output besides the headphone jack which kills the speakers, which I do not want to do. I bought an hdmi adapter that has a 3.5mm jack on the side that supposedly will give me the audio I want. If I plug the cable with two 3.5mm plugs into the adapter and the wireless transmitter to the headphones I get nothing. I have tried all the audio setting in the TV and still nothing out of the HDMI. Can someone please give me some guidance here?

Thanks in advance.