I managed to install VirtualBox and import Sage-7.2. When I click on the green Start arrow a windows with a brief message saying Booting CentOS 6.7 appears and then changes into a mostly white screen with the following elements:

A menu with File Machine View Input Devices Help

jupyter

Three tabs with File Running Clusters

A line with "Select items to perform actions on them"

Two folder icons with the names Sage and Sage 7.2

Two file icons with the names notebook-browser and sage-notebook.log

I clicked on notebook-browser and the screen showed the following three lines:

!/usr/bin/env bash

Kiosk-mode browser for the notebook

/usr/bin/chromium-browser --no-first-run --kiosk "$@"

I tried to calculate 2+2 but neither Enter nor Shift-Enter had any effect except moving to the next line.

Can someone help?

Thanks.