Godot error when using the right node?

Godot Version

Godot 4.3.stable.official

Question

When writing camera controller for ![this level layout](upload://nclEOGRtJeBawj6n0d002sekGbf.png), godot throws an error if I use ![this code](upload://3NqYWnNVDA07Sdr7MX4vQZBRpOc.png) and suggests that I need to use ![this node path](upload://y76cLJSrDmw9Sh3Nk9vydMiY074.png) instead. Is anyone familiar with this? Why is this so?