Wow. I'm an idiot. I always thought you had to have a QR reader app to use QR codes...
I just tried pointing the regular camera app of my iPhone at it and it read it immediately.
I learned that more by mistake a few weeks/month ago.
This was only added natively in iOS 12 I think
Yup, it was 11 or 12. All modern smart phone operating systems handle them natively now, but that is a fairly modern change. You used to have to use a 3rd party app.