Taking as reference the official doc¹ and doc² from Gitlabs CE, is possible to start just running as docker-compose up.
Go to http://localhost:10080/ as root
docker volume create gitlab-runner-config
docker run -d --name gitlab-runner --restart always -v /var/run/docker.sock:/var/run/docker.sock -v gitlab-runner-config:/etc/gitlab-runner -p 8093:8093 gitlab/gitlab-runner:latest