I have two suggestions you could try before investigating any further:
- Scenes are for handling of different screen sizes and proportions. You should always have scenes as top level items in your game window. Please do not put another Scene object inside a Scene (as is in your Flickable). You can just use Item there.
- If the Flickable should be scrolling up and down, the vertical direction is set correctly, but you also need to set the height of the content (like the commented out property contentHeight, you could try with contentHeight: childrenRect.height
You can test it on desktop with the shortcut keys 1-6 on the keyboard, this will resize the window in common smartphone/tablet sizes.
Hope this helps!