I have found another way as posted on BOI website for old phones.
Hi there, thanks for getting in touch. If your device is running on one of these older operating systems, and you do not update the device by 31 March, the existing version of the BoI app that you use today will not be supported should you have an issue. If you are unable to update your device we can order you a PSK. A Physical Security Key (PSK), a device unique to you which generates a code to enter into 365 online when prompted.