I couldn't find the author of the book but I saw "the Conjuring" and watched most of "The Conjuring 2" before it about put me to sleep. I couldn't find anywhere that said it was based on a true story as I believe the same as Tink. I usually watch some of that stuff or read some of it also but I wasn't impressed with either of those!
Since it is a story about the supernatural, it is hardly likely to be true, although it might be based on things real people thought they experienced.
I have serious doubts; actually, I would rather think that nightmares - and, eventually some horrible crime stories - inspired this horror movie.
I did not see it, so, I checked:
https://en.wikipedia.org/wiki/The_Conjuring_2
I couldn't find the author of the book but I saw "the Conjuring" and watched most of "The Conjuring 2" before it about put me to sleep. I couldn't find anywhere that said it was based on a true story as I believe the same as Tink. I usually watch some of that stuff or read some of it also but I wasn't impressed with either of those!