ECG app not appearing on Series 4 watch setup using Family Setup

I have setup a Series 4 for my Dad with Family Setup. There is no ECG app on the watch and when I connect to the watch from my phone and open the heart app there is no option to re-install the ECG app the way there is when I connect to my Series 6 watch watch using the same phone. I really want to have this app on his watch is there a way to do that?