The issue is in the landmarkData.json file, the problem comes from the tutorial page.
If you see, landmarks[0] gets you imageName = turtlerock
Now, if you go to Assets and see the name of the file it's named turtleRock, with capital R.
If you go to the JSON file and change the naming to turtleRock your preview will work.
For every other object on that JSON file, it works correctly
GastonSaillen
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My answer is below...
Download xCode 15 beta 6 since this version of xCode that you are using does not support your OS
https://developer.apple.com/download/all/?q=xcode