it’s means in many times(%95), your user not under docker group placed, or your post-install (docker group, user actions etc. steps) not completely done yet. For temporary fix, you can your docker/docker-compose command with sudo run.
kzorloglu@kzorloglu:~/projects/chameleon$ composer up #ERROR: Couldn't connect to Docker daemon at http+docker://localhost - is it running? If it's at a non-standard location, specify the URL with the DOCKER_HOST environment variable.
kzorloglu@kzorloglu:~/projects/chameleon$ sudo composer up