Slim Application Error - installation of Shopware 6 on local computer

So, the first option - installation of Shopware on Ubuntu which is on Virtual Box failed

The second option was about Docker Container. The istruction is here https://docs.shopware.com/en/shopware-platform-dev-en/getting-started/installation-guide?_ga=2.211923924.1779112066.1567410322-794630202.1567146750#docker-installation-recommended

But it this is not full instruction and you sent me  https://docs.shopware.com/en/shopware-6-en/tutorials-and-faq/virtual-box-setup#download-the-vm  and this one is also very confusing. What is described here? I see the continuation of the first version which I did and failed. \

Is this another version of what I did? 

Does this VM include Docker inside? 

Does it already contain Shopware or I still have to clone and install it?

I installed it but no idea what Is installed. The IP address is 192.168.0.3 

In browser by this IP I get:

Unable to find a matching sales channel for the request: http://192.168.0.3/". Please make sure the domain mapping is correct

Next instruction is 

Now the Connection via SSH is possible via IPoftheVM and Port 22

What does that mean??

Could you please write all steps from 1 to the last one of how to install shopware with Docker Container?