Perhaps a short explanation of terminology is warranted. When you see VST (upper case letters) effects are referred to. When you see VSTi (3 upper case and 1 lowercase letters) instruments are referred to. If you see iVST it’s some new Apple product (just kidding).
Rumdrum is correct that both VST’s and VSTi’s use the .vst or .vst3 file extension (we’re speaking Mac here). These extensions are usually presented in lower case letters, although some vendors may use upper case. Since OSX is not case sensitive, when it comes to file-names/extensions, it makes no difference operationally.
I have never said that it is an instrument. However, is it VST Effect? After checking out the product website (DAW Plugins: Orchestral Instruments, Drums & More | EastWest), I get the impression that it isn’t, but an effect that runs inside QL Play. If this is correct, TomcatToo should check that QLPlay.vst (or vst3) is installed (and this is an instrument).
By the way, thanks Rumdrum for the YouTube line. The full tutorial can be downloaded here, if anyone is interested:
http://musicalnotes.org.uk/Focus/Cubase%208%20First%20Look/Cubase_8_Pro.html