Because CC 2015 is a legacy software version, official Adobe Exchange downloads for this specific engine are sparse. However, you can find compatible 3D meshes on community platforms:

Photoshop will automatically create a 3D layer with the chosen mesh, ready for lighting, texturing, and rendering. Working with Mesh Presets: Top Tips for CC 2015 1. Customizing the Shape

Flattens the layer into a 2D plane inside a 3D environment.

: The most reliable format, carrying geometry and texture coordinates. 3DS : Ideal for legacy models and complex scenes.

3D Mesh Presets are pre-built, parametric 3D models included within Photoshop. Instead of creating a complex shape vertex-by-vertex, you can select a shape from the library, and Photoshop generates the 3D mesh. Common presets in CC 2015 include: Spheres, Cones, Cubes, Cylinders.