At the step #choose-the-bottle-framework, the instructions specify "Choose Python 3.8 (Bottle doesn't work with earlier versions):". However, Python 3.8 may not be listed.
An additional step is necessary early on in the instructions:
- In the user account settings, select the System Image tab.
- For python3 should run, choose Python 3.8. (If Python 3.8 is not listed, select a different value for Current system image)