App crashes after downloading data. – Pokémon Duel Review

On launch, after submitting birthdate and agreeing to EULA, the app starts downloading data. After downloading, it crashes. I've tried deleting and redownloading, turning off phone and restarting. No joy. Could be that my phone is too old (iPhone 5c, iOS 10.3) but it downloads and launches but crashes after initial download. Pls fix.
Review by Moonlightscribbler on Pokémon Duel.