App Compatibility

I have a iPhone 15 max, I just had a medical procedure done and need to access this app to use it properly. I can install the app via the AppStore but when it opens it says it must be ran on iPhone 14 to iPhone 11. I remember years ago you could tell the apps you were running a different/older iOS device for it to run properly is this still an option somewhere?  Any help or ideas would greatly be appreciated.