* Run `mix pleroma.instance gen`. This will ask you questions about your instance and generate a configuration file in `config/generated_config.exs`. Check that and copy it to either `config/dev.secret.exs` or `config/prod.secret.exs`. It will also create a `config/setup_db.psql`, which you should run as the PostgreSQL superuser (i.e., `sudo -u postgres psql -f config/setup_db.psql`). It will create the database, user, and password you gave `mix pleroma.gen.instance` earlier, as well as set up the necessary extensions in the database. PostgreSQL superuser privileges are only needed for this step.
* Run `mix pleroma.instance gen`. This will ask you questions about your instance and generate a configuration file in `config/generated_config.exs`. Check that and copy it to either `config/dev.secret.exs` or `config/prod.secret.exs`. It will also create a `config/setup_db.psql`, which you should run as the PostgreSQL superuser (i.e., `sudo -u postgres psql -f config/setup_db.psql`). It will create the database, user, and password you gave `mix pleroma.gen.instance` earlier, as well as set up the necessary extensions in the database. PostgreSQL superuser privileges are only needed for this step.