I have installed CDK, etc. from the "all in one" installer. Later, I tried to use Docker tooling. I opened the view "Docker Explorer". There was no connection shown. I tried to add a new one, but the system did not detect my default connection.
Later, I ran "Docker Quickstart Terminal" from the start menu. Now the "New Connection" dialog in docker explorer picked up the default connection.

As a user, I have no indication that I have to run the docker terminal in order to use the docker tooling in eclipse. If there are environment variables to be set up, the installer should do so. It is the reasonable expectation on Windows.