This repo is forked from https://github.com/CraftedCart/BlueprintRotationLibrary. This fork made the code a UE plugin. You can copy this plugin into your UE/Project plugins folder, it should just works(after compiling of course).
A collection of blueprint nodes to work with Quaternions within Unreal Engine's Blueprint scripting
Just copy the whole folder into your EnginePath\Engine\Plugins, or ProjectPath\Plugins if you prefer.
It's enabled by default, you can of course disable it in the BlueprintQuaternionLibrary.uplugin or in your project plugin settings.
I don't care what you do with this, I put this into the public domain. It's mostly just wrappers around FQuat functions anyway. <3
This project lives on GitLab (https://gitlab.com/CraftedCart/BlueprintRotationLibrary), however changes are synced over to GitHub (https://github.com/CraftedCart/BlueprintRotationLibrary)