The topic you referenced states:
After the Grey theme is applied, store pages will look like following:
You need to apply your theme after you create the theme's files.
Apply a theme
After you add your theme to the file system, you can apply it to your store. You apply a theme in Admin.
To apply a theme:
- In Admin, go to Stores > Configuration > Design.
- In the Store View drop-down field, select the store view where you want to apply the theme.
- On the Design Theme tab, select your newly created theme in the Design Theme drop-down.
- Click Save Config.
- If caching is enabled, clear the cache.
- To see your changes applied, reload the store front pages.
See this page for more information.