Getting fisheye materia

Hello guys,

I’ve used this tutorial, which works until the moment I need to plug it into camera/scene, unfortunately it wasn’t shown how to do it.

I’ve opened new project, FPS template. The best I’ve come far is:

Material Domain: Post Process in fisheye PP material, then added the material to Blendables of Post Process Volume

And plugged distortion map to Emmissive Color material input that way (you can see that it distorts chess texture just like in tutorial from above):

But it seems the distortion map needs to be zoomed into middle part to hide extreme stretching:

Of which I have no idea how to do. Any suggestions or questions?