Was this the case for you? Because it was for me. The readme in the mod did mention that some problems might occur if the first time you load a game when the mod is installed your character is mounted on a horse. But apparently they are not the cause since you have the same problem without other mods installed (if I understood you correctly).
I have tons of mods installed and thought that one of them conflicts with 'better horses'.
If you have the book in the game that means that most likely you did install the mod correctly. When I read the book nothing happens and there is no dialog box. Hi Angkorbeer, I have the exact same problem, but have not found a solution so far.
