WebGl is still not working, but I know what's wrong!
I debugged the launch in a console and it says that it can't find the file called "UnityLoader.js". This means it is probably missing in the zip you uploaded. When you packed the zip that you uploaded you must have forgotten to include the folder called "Build" and probably the folder "TemplateData". They are not optional you need them. This is where the actual game lies. The "index.html" file is just there to properly open everything!