Got it, thanks guys. Had to add lipsync to the optical but got it to work.
You should not be using optical if you are using ARC. It is fine to use optical, but you've missed doing exactly what you asked about doing.
ARC is a HDMI specific connection that allows audio to be returned from the TV to the receiver. Audio RETURN Channel. So, audio would flow out of the TV over the HDMI cable, back to you AVR. One HDMI cable, no optical cable, the optical cable should not be needed if you are using HDMI ARC.
Page 11 of the manual indicates that the receiver supports ARC.
PS5 HDMI OUT --> TV INPUT (not the ARC connection)
RECEIVER HDMI OUT --> TV ARC HDMI INPUT
That's it for connections and audio should pass from the TV to the Emotiva over the HDMI connection.
You could also just use the optical output of the PS5 directly to your Emotiva which bypasses the TV completely for audio.