No surround sound in a PS5, LG OLED CX and Anthem MRX 720 setup

Firstly, you will have to excuse my English – but here goes! J

I have a PS5, an LG OLED 65CX TV and an Anthem MRX 720 receiver where the latter – as you probably know – does not support HDMI 2.1. I have connected my PS5 directly to the TV and I am able to play games in 120fps but I have trouble with the sound as the Anthem now shows PCM 2.0. Shouldn’t I be able to get some kind of surround sound in this setup?

On the PS5 – in the audio settings – I have chosen "AV amplifier" under "HDMI device type" and in the "Number of channels" section I have chosen "5.1", as this is my setup. I have also tried various settings on the LG TV in the “Sound” section but as stated earlier, the display on the Anthem shows “PCM 2.0” no matter what I do. I have naturally also experimented with settings on the receiver.

So, do you have any recommendations to the sound settings on the PS5 and the LG TV (“PCM”, “Bitstream” etc.)?

I have read of different solutions from HDFury (“Hdfury Arcana”) and Thenaudio (“SHARC EARC HDMI”) and could this be the solution?

Thank you very much in advance and best regards
Jonas