This is a paid asset, but now you can download ProSurfaceSnap Free.
Detail this asset from Unity Store: Original Link
ProSurfaceSnap v2.0.2 (Latest version)
Welcome to ProSurfaceSnap!
ProSurfaceSnap is an editor extension which is incredibly useful for populating your 3D world with props. Ideal for terrain and mesh surfaces, with a very intuitive interface (mouse move to snap/rotate/scale/offset) this handy plugin will make level design and world decoration fast, intuitive and fun!
Per Layer Settings
• snap object to terrain;
• snap objects to meshes (no mesh colliders needed);
• support for spherical surfaces;
• rotate, scale, offset using the mouse;
• anchor pivot adjustment;
• hotkey customization;
• surface settings
• per layer customization;
The following assets are not included with the package but were used in screenshots and videos:
Mountain Trees-Dynamic Nature
Advanced Foliage Pack
Advanced Rock Pack
Skybox Series Free