HSO works nice as vst sound instrument set within Halion Sonic SE.
You need to read this page (especially the bottom "activation:):
https://www.steinberg.net/en/support/knowledgebase_new/show_details/kb_show/halion-symphonic-orchestra-version-overview/kb_back/2020.html?tx_p77sbknowledgebase_pi1[product]=38
If the new HSO installer is not included on the cubase 7 disk, I’ll advise you to contact steinberg support.
The demo installer is available on every cubase 6 disk and you own the license.
Tom