As visible in the attached image, when I apply a grass or ground texture to a plane, it all spreads around and looks like it is being stretched to fill the whole floor...
I cannot seem to find any settings that would address this. I have already triedx setting the wrap mode to repeat, according to this manual page...
Could someone please help me understand why this is caused and how I can fix it?
In the shader options you can change tiling on the X and Y direction. Greater tiling means more repeats of the texture on the plane. Tiling is defaulted to 1 when dragging a texture on which explains the stretched out look you got. For a fairly large plane try 100 by 100 or whatever fits.
To open the shader settings for the material you are using, select Forest Floor inside the inspector panel.