Go to Edit > Preferences then to the Add-ons tab. Click Install.

Choose the downloaded zip and click Install Add-on.

After the installation is complete it will show up in the add-on list. Enable the add-on by ticking the checkbox.

Open the 3D Viewport and press N to reveal the sidebar. All Blender-to-Unity tools live under the Unity tab: Tool, Collider, Lod, Export and Help.

Select one or more mesh objects and open the Collider panel. Pick a shape: Box, Capsule, Cylinder, Sphere, Convex or Convex VHACD (Windows only, requires the V-HACD executable).

Click creates an auto collider for every selected object, sized to its bounds. The collider is parented to the object and named {object}_Collider so Unity's importer can pick it up.

Shift + Click creates a custom collider on the active object from the other selected objects (requires two or more objects selected).

Ctrl + Click creates a bounding-box collider for the whole selection, and Alt + Click creates a single shared collider for all selected objects.

Each shape gets a colored, semi-transparent helper material (.box_collider, .capsule_collider, .sphere_collider, .convex_collider) so you can see the collider volumes in the viewport. Colors can be changed in the add-on preferences.

Open the Lod panel. The list holds reduction ratios (default 0.5). Use Add to append more levels, and save or load ratio sets with the Presets menu.

Create builds a LOD chain for the selected objects: {object}_LOD1, {object}_LOD2 and so on, each with a DECIMATE modifier set to the ratio from the list. Existing LODs are replaced on re-run, so the operator doubles as an update.

Shift + Create offsets each LOD's location so you can compare them side by side. Ctrl + Create builds cascade LODs, where each level is decimated from the previous one and the modifiers are applied. Ctrl + Shift + Create offsets the cascade LODs.

Shift + Remove deletes all LODs of the selected objects at once.

Rename renames the selected object, its child colliders and LODs, and their collections in one go.

Toggle Colliders and Toggle LODs show or hide the generated helpers. Shift + Click toggles recursively including children, Ctrl + Click toggles the selected collections, and Alt + Click deletes them (with a confirmation dialog).

Open the Export panel and set the Type: Export to Unity, Export to Disk or Both.

Add one or more destination folders with the + button, or use the Load Folders button (refresh icon) to scan and add subfolders of the active path automatically.

Choose the Selection mode: Objects exports the selected objects, and Collections exports the selected collections. Under Include, enable Children or Sub Collections and Materials.

Set the Shader Type (Standard, Standard Specular, Autodesk Interactive, URP-Autodesk, URP-Lit, HDRP-Autodesk, HDRP-Lit) and Surface Type (Opaque or Transparent). These are stored as custom properties on the objects so Unity's importer can create the right shader automatically.

Hit Export. The export runs in a background Blender subprocess with a progress slider. The FBX is rotated and scaled for Unity's coordinate system (100 units = 1m), collider helper materials are removed, and modifiers are baked (objects with armature modifiers are skipped). Alt + Click runs the export in debug mode.

To get colliders and shader types in Unity automatically, import the BUImporter_v3 script into the open Unity project (drag and drop, it should compile).

Install the com.unity.nuget.newtonsoft-json Unity package (required by BUImporter_v3). Open Window > Package Manager, click the + button, choose Add package by name and enter the package name.

Open Edit > Preferences > Add-ons and expand Blender-to-Unity. The General tab holds the Object Collection option (per-object collections for colliders and LODs), collider colors, the LODs Offset distance, and the Windows-only V-HACD settings.

The Export tab contains Factory Startup for subprocesses and the full FBX export settings: path mode, embed textures, batch mode, object types, custom properties, scale, axis conversion, smoothing, modifiers, triangulation, armature and animation baking options.