Reinstalled Android, lost keys

Hi, some time ago I reinstalled CyanogenMod on my phone (big upgrade), losing all my
installed apps and their data. I rarely use 2FA, and where I do, I usually keep the
session open, but for some reason I lost the session and now I can't log back in.

I have a backup from before reinstalling the system, can I get the keys back from there?
Where should I look for it? Where should I put them for FreeOTP to find them?

Thanks in advance,
Dani