The article is a checklist for myself, but for anyone else setting up PostgreSQL 10 on MacOS for having a SQL database in an Express.js application. You can leave out the Express part to just set up Postgres on MacOS.
Accepting payments on your own website can be a recurring problem. Often you'll find yourself avoiding it. There are platforms such as Gumroad which deal with this problem by outsourcing it. However, at some point you want to avoid these third-party platforms and introduce your own payment system.