Opera doesn't seem to have IOS versions on their archive site, and I don't actually know if IOS would allow installation from a site other than their App Store anyway - but if so maybe the developers can post one for you.
At some point, Opera Mini and Opera Coast too have disappeared from the available products in the app store.
The twin app called Oupeng Mini offered by nHorizon Innovation Beijing Ltd is still available but it gives the same error message on login attempts.
Opera data syncing on iOS device seems to be no longer possible...???
Anyone else tried to contact the support? I haven't received a response from them.