Which Oticon app should I get for Oticon Cros?

Hi I’m getting the Oticon Cros in 6 weeks time and am currently trying to find out a more about it. When i look on the App Store on my iphone there are two app’s available the On app and the Companion app and don’t know which app is the best one to get?

That is interested because the ON app has been removed from the Google Play store. The ON app has been obsoleted for all most a year and maybe longer. So i would say the companion app

@cvkemp thanks for that will do