Hi,
in Install Plone from its packages – Install — Plone Documentation v6.0, it is written: “ You will be presented with a series of prompts. You can accept the default values in square brackets ([default-option]) by hitting the Enter key, or enter your preferred values.”
A warning about forbidden characters should be added (it would be even better for this warning to be displayed by the script). At least the characters (, ) and ', which are likely to be used in the “description” step, cause errors.