All good!
I got it running. I think that tutorial needs updating.
import React from 'react';
import ReactDOM from 'react-dom';
import { FreeCamera, Engine, HemisphericLight, Sphere, Ground, Scene } from 'react-babylonjs'
import { Vector3 } from '@babylonjs/core';
ReactDOM.render(
<div>
<Engine canvasId="sample-canvas">
<Scene>
<FreeCamera name="camera1" position={new Vector3(0, 5, -10)} target={Vector3.Zero()} />
<HemisphericLight name="light1" intensity={0.7} direction={Vector3.Up()} />
<Sphere name="sphere1" diameter={2} segments={16} position={new Vector3(0, 1, 0)} />
<Ground name="ground1" width={6} height={6} subdivisions={2} />
</Scene>
</Engine>
</div>,
document.getElementsByTagName('body')[0]
);