It’s actually your statement that makes zero sense. Halion 4 and Halion 5 are sample players and editors (and many other things, as well). HSO is basically a set of samples, which play perfectly in both Halion 4 and 5. It also includes its own standalone player, but is not a part of Halion 4 or 5. 16 bit refers to the bit depth of the audio files in the sample set, NOT the code base of the programming.
If you already have HSO licensed, all you need to do is reinstall it. Download it from your account, or from the trial version DVD set. That was included with the Cubase 5 installation disks, if you have them, and possibly other packages, as well, I don’t remember (Halion 4, perhaps?). Sounds like you must already have them, though, if you installed them at any point. BTW, don’t to try to register it again with the trial code if you already have the full version license.