Install extension pack right from Marketplace OR from VS Code (View → Extensions)
Create empty file named .kata into your Notes directory → open that directory as folder. If you have no notes yet create at least one .md file in that folder manually.
If you want totally the same "screenshot-like" appearance, copy these settings into workspace settings file (hit F1 → Preferences: Open Workspace Settings (JSON)). Pay attention to font (it is depeends on operating system). Check editor.fontFamily setting and change fonts if needed.