I am just installing the pack by finding the folder and pressing "save" as instructed, but strangely for the colored ground tiles of different types(stone, dirt, etc) it does not fill the tile completely- leaving a white border around it, and not touching any adjacent ground tiles..any tips?

I have the same problem...it seems broken. Even if you import and custom zoom in the tiles, after saving and reloading the thick white outline returns like the tiles are too small. Seems to be an issue with this pack.