Starting Docker in Container Station

Hello to everyone, many thanks to productive and useful forum community. I am newbie in Docker and containerization, and i am having trouble to start Docker. I have installed few containers using default images on my Container Station in QNAP. When i tried to open a default image containter with installed Docker version 18.06.1-ce, build e68fc7a i got an error

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?`

I have similar issue when i try to open a docker in Ubuntu 16.04 (also downloaded from docker containers) i got error

/etc/init.d/docker: 87: ulimit: error setting limit (Operation not permitted)
My other containers (Owncloud and Nextcloud) are working fine.
Thanks in advance.