I am also having the same problem, running IOS 9.3.2 (latest), have tried using WiFi and 4G (with mobile data ON). Can see the "UPDATE" available in Itunes, but when I click it it just goes back to "UPDATE". I am able to update other apps (for example this morning's Pokemon GO update), just not Dominations. My wife, running same phone, same IOS level, same carrier was able to update hers while sitting beside me.