Problem with docker-compose under WSL2/Ubuntu20.4

Just at the beginning of the course, (environ setup : lesson https://academy.jfrog.com/path/conan/conan-essentials/590849 )after issuing the command:

> ~/projects/training/docker_environment$ docker-compose up -d

I've got an error message:

> 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.

I am using Ubuntu 20.04 on WSL 2

Start by reproducing `docker-compose up -d` from `~/projects/training/docker_environment` on WSL2 with Ubuntu 20.04. Check whether the Docker daemon is running and whether `DOCKER_HOST` is set; done means the command connects to Docker and starts the environment without the reported error.

Written by the indexing model from the issue text.