File README.SUSE of Package pgagent

Run pgAdmin 4, open the server connection and select the database where you want to use pgagent.

Then open the Tools menu and choose the Query Tool.

Write:

CREATE EXTENSION pgagent;
CREATE LANGUAGE plpgsql;

and press F5 or click on the execute button (the one with the ray icon)

Note: If you get an error saying 'language "plpgsql" already exists' then remove
the CREATE LANGUAGE line and execute the code again with just CREATE EXTENSION pgagent;

Once it's executed successfully, select the server connection again, right click on it and select "Refresh...".

You should see a new "pgAgent Jobs" entry in the database tree in pgAdmin.