I can't quite remember the Arturia installation procedure. Added to this, I don't know your level of computer expertise. With this latter in mind, I hope I don't in any way patronising.
Usually, when you install a program that comes as standalone AND plugin, you have to specify or accept a path for each (2 plugin paths if using 32 and 64 bit). I wonder if the Spark plugin specified a wrong location? Perhaps (and this is just an example) it installed to something like:-
C:\Program Files\Arturia\VST
when it should have gone to:-
C:\Program Files\Steinberg\Cubase\VST
or something like that.