Happy to hear that you joined the challenge. The introduction i wrote is using pytorch for the deep learning agent (DQN). If you are using conda you can install it by running this command in your conda environment:
conda install -c pytorch pytorch-cpu. Note that this however is only the cpu version, which is sufficient for the introduction. If you need GPU support follow the instruction on the torch homepage.
If you are not using a conda setup yet I suggest you set it up following the instructions here: Flatland-Challenge-Starter-Kit.
Hope this helps. Otherwise don’t hesitate to ask if you get stuck.