Hi Querty, thanks a lot for the feedback,
I suggest you also read the article on push notifications linked at the beginning to make things more straightforward for you on the subject, and I’m sure it will make everything clearer even for a beginner.
The code in this article is intended to illustrate and explain the concepts. It was not written to run, while the one on the repo is more suitable for this purpose.

If you were so kind as to show me the typos, I would correct them immediately.

Let me know if you need further support on this topic. Maybe we can organize a live coding session or something similar.