Try reading. I installed it on a USB drive, and it wouldn't install ALL programs. my plan was to use it to repair broken Windows, and one of the tools required would be A/V. But some have dropped support for Ubuntu.

https://help.ubuntu.com/community/Antivirus

So, if I've got a broken windows PC, I'd like to boot from USB and repair it, whatever the problem may be. That includes have tools to diagnose the problem. Not much use if I can't install the tools or they are no longer supported.