That error message suggests that you’re trying to use docker-in-docker (the highlighted “services” in the screenshot also suggest that) on a (docker, I haven’t tried on anything else) runner that doesn’t support it.
I have no idea what “Gitlab.com classic gitlab runners” means, we have a GitLab setup on-premise with our own runners, I have no idea if GitLab offers anything for SaaS users (I know they can set up their own).
Need to edit → /etc/gitlab-runner/config.toml
Problem is here, need to add "/var/run/docker.sock:/var/run/docker.sock" to volumes volumes = ["/var/run/docker.sock:/var/run/docker.sock", "/cache"]