The cards are all prebuilt game objects. If you look at the hierarchy, you will see:

These tiles seem to have been prebuilt and the UV's on the faces created externally.

Each card has its own prefab:

Which in turn is associated with its own model:

You can open these in a 3D modeling application and look at the way they were put together.

All of these object prefabs are instantiated in the game world, and are kept just out of the camera's frustum:

To recreate this on your own, you'd need to grab a "card" model (this one will do) and open it in a 3D modeling application. You would then set the UV's for each card based on your texture, and save one per face.

Another way you could change these to your own drawings is use the existing models and existing UV's and take the texture files and replace the images on the texture.