https://pixllab.github.io/URSDocumentation/welcome/notes/2020/11/15/Gazebo-Map-Making.html
I don't know what world.launch in number 9 of the homepage above means and what it contains. If anyone knows about this, please reply.
The launch file you are looking for is located, as mentioned, in the launch directory, and it github you can find it in here: https://github.com/PIxLLab/URSSimEnvironments/blob/master/urs_wearable/launch/world.launch