I went through a similar situation, the IOS app worked fine on my iPhone but not on my “older” iPad.
I cancelled the 7 day free subscription before it charged my Apple account.
I installed “BlueStacks” on my Windows PC and am able to load Google Play Store and Android Apps on my PC. The app works great on my PC.
I will miss the portability of my iPad and iPhone but in reality I use my PC over 90% of the time anyway so this was a great solution to be able to get the app with the Guitar-aoki.
I’m very happy with it on my PC.