Other Using render Texture of Object with Transparent background

Hello there,

I recetly got lost and asked this question in another forum but got redirected here due to it being the wrong Forum so now im trying my luck here.

Im using unity 2021.3.4f1. and HDRP

So what i want to do is have a a preview of a selected character in the main menue of my game. I followed

to get what i want and it works fine so far except that i want to have transparent background on my render Texture but the option he shows in the video no longer exists and the best i can do is use a black colored background.https://imgur.com/a/5X8Gogy this is how it looks when i try to use "none as background". I've searched around in the webs for quite some time trying different things but some option is always missing in the unity version i'm using any help or pointers even if the answer is : "this is the entirely wrong tool look for x instead" would be much appreciated.