what f-droid or droid-ify wallet should I use?

I just learned there's something called a 'wallet' I need to download to use public transportation where I live because I'm supposed to download the qr code there. I screenshot the qr code found in my profile but the company insisted per email I need to use a wallet, either google or apple (and this is android).

Several questions:

why doesn't it work to screenshot the qr code?

I won't use anything google related. What f-droid or droid-ify wallet should I use?

any other workarounds i should be aware of?