I purchased a sound library from LoopMasters.com. It came with Sampler Patches for Halion and Kontakt. (I have Halion SE and I have other Kontakt instruments).
How do I install these .nki or .fxp files so they show up as an instrument in Cubase Pro 11?
As @misohoza points out you need the full Halion to go that route.
I’d recommend not purchasing a library until you understand which VSTi’s can load it. For example some Kontakt libraries will load into the free Kontakt Player while others require the full (i.e. paid) version of Kontakt. The libraries should specify exactly what it works with - pays to double check you have what it needs.
I had followed those instructions and loaded the .nki files successfully into the Kontakt stand-alone app - I was able to play the patches using my piano. But I don’t know how to access them from within Cubase.