A large proportion of the population do not HAVE smart phones.
Interesting question. I had vaguely thought about the difference and surprise surprise, from our good friend Mr Google:-
17.9 million smartphones
When most people hear 'mobile', they tend to think of smartphones and feature phones. These devices are common - there are an estimated 17.9 million smartphones in Australia (Statista, 2019).
Mobile Nation 2019 - Deloitte
The next question is what is "large" I would think maybe 20%.
From our survey here 37% have not downloaded the app, and I don't remember any one quoting not have a smart phone.
If we can assume Mr Google is roughly correct, lets say 15 million smart phones in Australia and maybe some people have two we could then conservatively say 12 million people in Australia have a at least one smart phone then only 50% of the smart phone owners downloaded the app.