The first step to get this running is to install the dependencies specified in requirements.txt. You may do so by executing pip install -r requirements.txt in a shell.
Next, execute sh start_server.sh in the shell to start the Flask server that processes image-generation requests.
If you are running this on a remote server, you also have to set up ngrok tunnelling. To do this, install ngrok, then execute sh start_ngrok.sh in a shell. You will then set the ngrok link you receive in the HOST constant in src/App.js in the Mercury UI. Note that since the ngrok link may change, you may also have to change the value of HOST, multiple times.