That's right, to say goodbye when parting. The English "Good day" can be used like that. But there's no "Good day" greeting that can be used when one meets someone.
Works in German: ,Guten Tag‘ is a common greeting when meeting.
It used to be used as the ‘good day’ parting in English. But that’s a long time ago.
Still, in English it isn’t very common anymore either, if I’m not mistaken.