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.