If I take the bottom ring off then it all sits flush on the top of the fork, as I would have expected. But it would then be the bare bearing sat on the fork top which can’t be right.
You need the crown race, "bottom ring".
It should be a tight fit unless it has a split in it. You will need to press it onto the fork and press the headset cups into the frame.
You will need press tools for this.
If I take the bottom ring off then it all sits flush on the top of the fork, as I would have expected. But it would then be the bare bearing sat on the fork top which can’t be right.