Instructions:

1. Install the .zip file you downloaded in Blender > Preferences > Add-ons > Install
2. Modify hotkeys to your liking under Add-on preferences (I recommend keeping them simple and accessible). Default hotkeys are A for Full Bar and B for Mini Bar.
3. Use hotkey to toggle either Mini Bar or Full Bar.
4. For Mini Bar, you can customize it by pressing N and navigating to the Node Bar on the right side of the Shader Editor, in the N-Panel.
5. You can move the Node Bar by clicking and dragging on it with the Right Mouse Button. You can resize it with the Middle Mouse Button.
6. Don't forget to Save Changes in the N-Panel, if you have customized Node Bar or changed its position. (This is the same as pressing saving Preferences in Blender).