Can't upload app to QT Design Viewer: "QtQuick not installed"

[ploux]

Trying to upload my app (the tutorial Todo List) to Qt Design Viewer as per:
https://www.youtube.com/watch?v=RieOEQXQsHQ

but get this error, saying that module "QtQuick" is not installed. Using Qt Design Studio 4.2.0 on Linux Mint 20.3

[jsulm]

@ploux So, is QtQuick module installed?

[ploux]

@jsulm I'm sorry, I don't know. How do I check/install it if it isn't?