Dear Carolyne
It appears that the distribution has changed since I downloaded Cosmos. The correct instructions are as follows:
There is a file called COSMOS-DESKTOP, which when double clicked will open COSMOS on Unix-based computers, e.g. Mac, Ubuntu, etc.
The other file COSMOS-DESKTOP-WINDOWS.bat is for Windows computers.
So, if you double click on COSMOS-DESKTOP on her Ubuntu computer it will open, as long as you has Java 8 installed.
The README for COSMOS Desktop version 1.1, which is now being sent out to users, is being updated.
Best wishes
Rob.