Textures not showing up in launched HTML5

hey everyone!

I wanted to launch a small test of mine direct to a browser by using the HTML5 launch in Unreal ( I use Unreal 23.1)
However, textures are not showing up. I am using substance sources.

I am very new to the area and dont know much about web dev.
Do i need to build my game for mobile?
If yes, what kind of textures can I then use ?

hope you can help me out

all the best