for "Lego Material for Blender"
This document will list some common problems and solutions.
Is this material compatible with EEVEE?:
No, it is built for cycles. Although you can technically use it in EEVEE, I have not put in any work to make it more compatible. One of the main reasons for this is that the material is quite complex, so it slows down EEVEE a lot, even in very simple scenes.
How do I even use it?:
I recommend you link the node group into the Blender scene you want to use it in. If you don't want to do this, you can also just copy and paste the group into your scene.
Textures aren't showing up?:
This could be because you haven't plugged in a texture coordinate node to the vector input on the material. This is required for the material to work. Also, play around with the scale to verify it isn't wildly off, making the textures too big or small.