I'm working on the User Interface API Trailhead. 

I have installed Docker and added settings to Connected App and CORS. 

Getting an error when I execute: 

docker-compose up -d                  
[+] Running 0/2
 ⠿ config-server Error                                                                               2.9s
 ⠿ registration-server Error                                                                         2.9s
Error response from daemon: pull access denied for ccc/config-server, repository does not exist or may require 'docker login': denied: requested access to the resource is denied

Here is the contents of docker-compose.yml:

$ docker-compose config
services:
  config-server:
    image: ccc/config-server
    networks:
      default: null
    restart: always
  registration-server:
    image: ccc/registration-server
    networks:
      default: null
    ports:
    - mode: ingress
      target: 1111
      published: 1111
      protocol: tcp
    restart: always
networks:
  default:
    name: recordviewer_default

Trailhead link: 
https://trailhead.salesforce.com/content/learn/modules/user-interface-api/install-sample-app?trailmix_creator_id=00550000008Dq3eAAC&trailmix_slug=developer-trailmix

Thanks in advance!