I have followed the post-installation instructions but still can't run Docker without sudo

Question

I have followed the installation instructions here, including the post-installation.

I have then opened a new terminal. Here's what I get

$ docker run hello-world
docker: Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post http://%2Fvar%2Frun%2Fdocker.sock/v1.40/containers/create: dial unix /var/run/docker.sock: connect: permission denied.
See 'docker run --help'.

I am using Ubuntu 20.04

Answer 1

Turning my machine off and on again solved the issue (logging out and back in again, as it says in the docs, didn't work for me)