I didn't check the pack but judging by the screenshots they aren't seamless, I only checked the top one to be sure though. Another issue likely caused by them not being seamless is that the normal map's edges use undesired angles(as made evident by your 3D renders). If you have Photoshop then a few minutes should be enough to make nice seamless images for almost any source material(and by nice I don't just mean blending the corners) and only then should you make a normal map. Also, normal maps are nice, but ones generated directly from the diffuse textures(as I assume these are) aren't really anything people would pay for as it's so easily done(using xNormals for example) and it doesn't provide any interesting features when rendered; after all, the angles are being extrapolated from the diffuse texture so it can't guess detail that you know should or shouldn't be present.
Lastly, your images appear to be of some random rectangular size which is nice for stuff you've just taken with a camera or if you want it in a frame. But for games you'd want those to have power of 2 dimensions for both speed and backwards compatibility, plus some D3D surfaces require both dimensions to be a power of 2.
