I'm new to Unity and game programming, so I apologize in advance for any embarrassingly bad stupidities.
I'm not having any luck trying to reproduce the RenderTexture example at the bottom of this page: https://docs.unity3d.com/2022.2/Documentation/Manual/class-RenderTexture.html
The only difference is that I'm trying to recreate it in a 2D project, so instead of a 3D cube, I'm trying to apply the RenderTexture to a flat square. The issue is that nothing is appearing in the square once I set everything up.
The setup is (not everything, but hopefully enough):
I've created a PNG file my sprite graphic, which is just a single color (white) object on a transparent background. I put that in my Assets directory.
I went into Unity and dragged that sprite from the Project window into my scene in the Hierarchy window. I moved the sprite out of the main camera area.
I created an auxiliary camera and pointed it at the sprite.
I created a RenderTexture and assigned it to the TargetTexture of the auxiliary camera. I set it up to be Orthographic and sized it appropriately so that the sprite is appearing in the aux camera's preview window. It's just a white image on a black background.
The instructions say to create a cube, but since I'm working in 2D, I've created a Square sprite.
The instructions say to drag the RenderTexture onto the cube to create a material for it, but that doesn't work for me. It doesn't do anything to drag the RenderTexture onto the Square.
I guess this is point where I should stop. I went further, creating a material and stuff, but it didn't get me anywhere.
I just want to know why this doesn't work. What am I not understanding about this?