We provide 2 different versions of this model as assets.

One which contains all textures at 4K resolution, and another which contains all textures at 2K resolution.

It's really up to you which version to use, and this depends on your needs. If the model will be the main focus of your renders, and you'll be generating closeup renders, we suggest for you to use the 4K version. On the other hand, if you need to save memory, especially if you're using GPU render and you don't have a lot of VRAM, or if the model won't be the main focus of your render, we suggest to use the 2K version. 

Since these two versions come with all the external data packed in the Blender file, you just need to save whichever version you chose (2K or 4K) in your Assets location.

The screenshot above shows Blender's default location for the Assets folder.