If you are talking about the plugin, just make sure MM knows where to look for not only that, but any othr plugins you have in the same folder. Kontakt player works fine for me. I have UVI workstation too, but find the memory demands are often much for my system (windows 7 Pro and 32 gig DDR3 RAM) from within MM. Any number of other vst's including Izotope Iris, Massive and various other hefty synths work fine. Always had problems with Sonovix efforts though. That may just be my system rather than MM.

Also - I've reverted from the latest version of MM Premium (version 2019) back to version 2018. 2019 is an absolute pig - crashes, misbehaves on playback won't export mp3 properly first time - you name it, it has caused problems for me. Once they sort it, it will be fine, but boy are they taking their time about it.