I can confirm that this is confusing to users, particularly those of us who are new.
The Apple App Store description states:
... which, when combined with the 1-year-old publication date, does lead one to believe they need Version 4 (not 5) to be compatible.
Luckily there are forums like this to find clarifications, as it certainly isn't clear from the app description.
@fenderman, do you by chance have any connections with the iOS app developers to either nudge them to revise the description, or have any news on when the app might be updated next?