The best I can advise is try to access it via the online banking website, if available. Otherwise, you simply cannot use mobile banking apps unless you have some way to emulate a sufficiently "verified" Android environment somewhere (on your phone or some VM somewhere else), and use that to open the app.
I would never try to do online banking on my phone if possible.
The banks have however decided that issuing separate security dongles is too costly, so instead they forced us all to install an app that acts as a security token.
So I cannot do online banking without the mobile app.
I would try to call them and flat-out tell them that you don't own a smartphone. Just tell them that you're using a dumb flipphone to communicate. Maybe they have a way to authenticate via SMS or alternative means. Else that would mean that peopler from an older generation who still don't have smartphones are just excluded from using this bank, which would be strange.
Else your only option is to buy a cheap android phone which you only use for this login. In a way that makes your banking activities even more secure because you're only using the device for 2FA codes :)
It matters, because your insecure device will be sending data to outside servers without your control, possibly with buggy software interceptable by hackers. So your 2FA codes could be technically intercepted before you know it.
