@eric3 Thanks for responding. I am leaving this comment so it is helpful for anyone else seeing the same issue.
The NetModel loads and works without any error on Wolfram Mathematica on a desktop. So if you are trying out example related to the ChatGPT book, use Mathematica installed in your desktop.
The NetModel does not load on Wolfram Alpha Notebook (it may be due to less available memory to load the model).