We recommend that you download the AV material to a safe folder on your computer.
We also recommend that you then ALSO copy these files to a USB stick and keep this with your printed book as a backup.
Use this USB to copy the files onto your computer or network when you need to.
Do not actually use this USB.
Wherever practical, run the AV from your computer and NOT from a USB.
If you must use a USB, for example if you are moving from class to class and do not want to copy the files to every computer, do so from a COPY of your original USB.