Error response from daemon: Container [id] is not running after entering PiVPN user password

I am running the bash script on a clean install of Raspbian Stretch using Docker. For some reason it says the container is not running. When I run docker ps there is no container running. I am fairly new to Docker so perhaps I am doing something wrong, but it is not clear to me if simply running your script and having Docker installed was all I needed to do. Thanks!