This repository is a Unity project which contains the Behaviour Tree Editor package.
The package and documentation is located in this repository here: https://github.com/thekiwicoder0/UnityBehaviourTreeEditor/tree/main/Assets/BehaviourTree
The minimum version currently supported is Unity 2021.3. This is due to the need for this feature: https://docs.unity3d.com/ScriptReference/SerializedProperty-managedReferenceValue.html
To install the editor in your project, you can either install directly from the Package Manager via a giturl, or by manually cloning this repository and creating a custom package.
(Or just copy the files if you know what you're doing)
The easiest way to install the package is directly from Package Manager in Unity via the Add Package From git URL using the following url:
https://github.com/thekiwicoder0/UnityBehaviourTreeEditor.git?path=/Assets/BehaviourTree/
This has the added benefit of being able to easily update the package from within your project.
All files will be installed to Packages/Behaviour Tree Editor
See https://docs.unity3d.com/Manual/upm-ui-giturl.html for Unity's official documentation on installing packages from Git using the Package Manager.
Alternatively, you can clone this repository and create a .unitypackage file manually by running the Export Package command on the Behaviour Tree folder within Unity.
The exported package can then be installed into your project using the Assets->Import Package->Custom Package command.
All files will be installed to Assets/BehaviourTree
See https://docs.unity3d.com/Manual/AssetPackages.html for Unity's official documentation on creating custom packages.