Paragon Ice Lands - Terrain Squares?

I’m fairly new and this is my first post on the forums so apologies if it’s in the wrong section or whatever.
But, I just downloaded the Paragon Ice Lands pack and started making my own custom game…
I designed my own custom controls, Base Camp and I just tried replacing the default terrain block with my
own; I set in the Ice Lands snow texture and it gave me a huge checkerboard. I tried re-building it and even
changing the textures but it’s still there.