But I have the pro version, I think. See below:
did you buy spectralayers? if not then you do not have pro. and it will be in the “my product downloads” if you own it. there is a stripped-down version included with Cubase.
There is only one SpectraLayers application for each version, which runs as Pro, Elements, or Go depending on your licences.
Unless you bought a licence for SpectraLayers Pro 11, you can only use the SpectraLayers Go featureset based on your Cubase licence. Just because you can download something with Steinberg Download Assistant doesn’t mean that you have a full licence for it.