is downloading Cubase LE4 possible?

Hi, just bought a new computer and am trying to reinstall my (I know rather ancient) Cubase LE4 to run my Omega Lexicon music interface. I have the CD from when I bought the product, unfortunately, no DVD drive in my new computer! I can access the original activation key via my Steinberg account. Can I download LE3, or should I just buy the latest version? Will the Lexicon Omega interface work with the latest version of Cubase?
Thanks in advance!