The steps you describe are actually only used when developing for the framework standalone (the adapt create course command you reference for example, has nothing to do with the authoring tool).
Have a look at the following wiki articles for more information:
In terms of your problem, the first step is to cd into the directory containing the authoring tool files - from here, you can run:
- node upgrade to upgrade the authoring tool version, and the framework used in your installation the authoring tool.
- grunt build to build the front-end of the authoring tool web app.
- node server to start the tool. You can then navigate to http://localhost:5000/ to run the app.
If you're still having issues previewing, there may be something else going wrong. I'd suggest reading the installation guide carefully to make sure you have everything set up correctly.