The application requires a redis db to be running on the system. For example use: docker run -d -p 6379:6379 redis:5.0.4
If the redis is run in a docker container please verify that the IP address is correct. Right now it is hardcoded inside the index.js file.
The application can be run inside a docker container as well, just make sure the application and redis are running on the same network and can reach eachother.