I’ve checked this weekend as promised, just didn’t got the time until now to report my findings here (with christmas and all going on).
It’s included in the base game and (therefore) also in the launcher, but yeah, you’ll have to install it again manually every time you update the game, which seems to cause confusion, as I see more and more threads pop up about this (like this one or this). Let’s hope there will be a solution soon.
In the meantime, I’ll leave a link to the mod’s readme here in case someone stumbles upon this post while searching for a installation guide. Credit: This readme was linked first by @Zhilkin in an other thread about this mod and he also points out how important it is to move the files, not to copy them.