First set the configuration options in postgresql.conf:

wal_level = logical

The other required settings have default values that are sufficient for a basic setup.

pg_hba.conf needs to be adjusted to allow replication (the values here depend on your actual network configuration and user you want to use for connecting):

host all repuser 0.0.0.0/0 md5

Then on the publisher database:

CREATE PUBLICATION mypub FOR TABLE users, departments;

And on the subscriber database:

CREATE SUBSCRIPTION mysub CONNECTION 'dbname=foo host=bar user=repuser' PUBLICATION mypub;

The above will start the replication process, which synchronizes the initial table contents of the tables users and departments and then starts replicating incremental changes to those tables.