Old version and wont work

I didnt know Apple left things on their website that wouldnt work on a 5S with the latest IOS

I paid and downloaded but cant even open the app to get to app support and communicate with them. Have deleted and reinstalled and restarted phone several time.

Rick73018 about ITGO - Interval Trainer GO - The Ultimate Gym and Outdoor Timer for Cardio Health, Fitness and Well Being