That will unpack and install the mod in the appropriate place. You can install any mod manually by downloading the zip, and then using the big green + in the NMM to find the file and add it. Book of Silence only has default 2k res, but there are some hi-res 4k options on separate armor pages, as well as some different options not found in the Book of Silence collection (brighter hide fur, etc). It might be a better idea to just go through Cabal's Nexus page to look at all the armors.
If you use the installer, DO NOT install the glass variants or differently ebony, as those add a non-converted esp to add standalone armors of the different colors. The default retextures work perfectly well in SSE. For default armors, the best around are from Book of Silence.
