I tested MW3 in iOS 11.0 and it worked perfectly fine. Are you using iOS 11 or you already updated to 11.0.1? Or you're using the Beta 1 for iOS 11.1?
Kathi is referring to MoneyWiz 1 for iPhone/iPad which sadly no longer works on iOS 11. We have more information about this here: http://wiz.money/knowledgebase/will-moneywiz-work-ios-11/
We have already contacted Kathi via e-mail about possible solutions to this situation.