The source code is available at github. Download or clone the code and execute the following commands from a terminal to install its dependencies..
sudo apt-get install git
git clone https://github.com/ibmtjbot/tjbot.git cd tjbot/recipes/speech_to_text npm install
I haven't used Github before. How can I download the code from Github?
Here are the instructions for how to clone a repository from github if you have not done that before.