It was pretty easy to get up and running with Docker Compose:

  version: '3'

  services:
      mysql:
          image: mysql:8
          environment:
              MYSQL_ROOT_PASSWORD: root
              MYSQL_DATABASE: matomo
      matomo:
          image: matomo:4
          ports:
              - 4000:80

This lets me in at localhost:4000 and I just enter "mysql" as the DB host, "root" as the username & password and "matomo" as the database name, and it's basically done.

Of course, I probably have to point it out or someone else will, that it's a bad idea to be using the MySQL root user, instead of creating a user with the rights that Matomo needs: https://matomo.org/faq/how-to-install/faq_23484/