I use both in tandem with no problem at all.. (I don’t use the latest phone, either.)
The reason I use Diabox is because I don’t need to open the app to see my numbers? It can create a “widget” on the Home Screen of the phone with a constant read out..
I use sweet dreams and the Libre app but I have to also use the Libre link app as well otherwise it doesn't work on my iPhone and watch which I get the widget and readings on my phone and watch