You may not like my answer, but it’s reality. It would be no different than [Mod Edit] complaining that the latest version of AutoCAD won’t run on a Windows XP based desktop.
Update your phone’s Android OS to something at least close to current. Quite certain that there is LOTS of other apps that won’t run on Android OS 6 (I can name a few).
MOD NOTE: Post edited to conform to the Community Guidelines.