engine.cfg is for Godot 2.1
project.godot is for Godot 3.0
What tutorial are you following? It sounds like you may be trying to follow a 3.0 tutorial but you downloaded the 2.1 binary. On the docs page, in the bottom left there is a version. If it shows "2.1" or "stable", then you're seeing the 2.1 docs. If it says "latest", you're looking at 3.0 docs.