Importing Heightmap [Noob Query :)]

Hi ,

I am a Noob . I am trying to import custom heightmap in unreal engine using this tutorial . Creating and Using Custom Heightmaps and Layers | Unreal Engine Documentation .
As mentioned there I saved the png image from this page and imported it using the landscape page .

Looking Close I see these tiles .

I am not sure what is going on , but my thinking is that the tiles are not getting stitched properly with adjacent tiles and there is a small bunp or a an edge in the surface .

Is there a way to smooth it out ?

And can someone guide on how can apply my own texture on this terrain .

P.S. The bigger problem that I am trying to solve is importing real world GIS data (Elevation, Raster and Vector) into unreal engine to build a simulation on top of it . Any insight in this regard is highly appreciated .

Thanks in Advance.

It got resolved by rebuilding lighting.