1. You have broken proportions. You need to to sync Size (in Scene) and Width / Height (Pixels).
2. I think you have a camera is very close to the map. Try to position the camera a bit further away from the map.
3. If resolution is not enough use 2560x1536.

Mine looks stretched too much.

I used Size(in scene) X 768 Y 1280 values.

First, a few thoughts about this:
1. Galaxy S6 Edge has a resolution 2560x1440. That you have good performance, I recommend to reduce the size of the map twice.
2. Each side of the map should be N * 256, so you need to use a 1280x768 or 2560x1536.
3. For mobile devices, we strongly recommend to use the tileset.

For Tileset:
http://forum.infinity-code.com/viewtopi … d=920#p920

For Texture:
You need to create a new texture, set it to the source display, and use OnlineMaps.SetTexture.
http://infinity-code.com/doxygen/online … 118f451394

I have a small question about the size of the map.

If I install it on my Galaxy S6 Edge, I see small portion of grey area.

How can I change my size of a map according to device width and height? vertical or horizontal?