Q: I downloaded an app but it won't accept my username or password.

What is the App.   Was it downloaded from iTunes?

If it is not an iOS app it won't work.   Apps from the App store are for Macs, Apps from iTunes are for IOS.    Mind you, I don't understand why it allowed you to download it to your phone, unless the developer has made it both ways.

Have just made another search.   You must have downloaded it from the iTunes store ... not the app store.   So it is an IOS app'   It should therefore work.   Contact the developer.

Thank you for the star.  Please let us know what happened; it may help someone else.

Actually the iTunes app on a Mac is divided up into a number of separate apps on an iOS device. Music and videos are from the iTunes app. Apps and games are from the App Store app. Books are from the iBooks app. Magazines are from the Newsstand app. Podcasts are from the Podcast app. Etc.

Thanks Dah*veed.   It seems a bit of a mess to me.  It needs some form of a listing, perhaps under an all embracing heading of purchases.

You will find purchased music, movies and TV shows in the Purchases list in the iTunes app on iOS. You will find purchased apps & games in the Purchases list in the App Store app on iOS. You will find purchased books in the Library of the iBooks app on iOS.