Having trouble following part 9 of PUN Network tutorial

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I'm following the PUN Network Tutorial found here:
https://doc.photonengine.com/en-us/pun/current/tutorials/pun-basics-tutorial/player-ui-prefab

The trouble that I am having is that in the sample code it puts PlayerUiPrefab, without defining it anywhere. I've tried putting it as a component and then loading it, but it also doesn't work. Would anyone be kind enough to point me in the right way?