I need to use an iPhone banking app on an iPad because the iPad app doesn't have TouchID enabled

I need to use an iPhone banking app on an iPad because the iPad app doesn't have TouchID enabled, but the iPhone app does. However, the TouchID doesn't seem to work on the iPhone app on the iPad even though it works on an actual iPhone. Is this a compatibility issue with TouchID not being able to properly interact with an iPhone app on the iPad? Or is this an issue that the app developer needs to address? I work at a bank and we are trying to help an elderly customer that has difficulty with passwords, etc. due to poor eyesight and really needs the TouchID abilities. Thanks!