Yes it's really weird as it says the app is too old and thus unsecure, but it downloads fine on a more recent phone than the A12, that's just as old as the final version of freeflight that's from 2021.
And yea I didn't sideload it via softronic because of the fear a russian hacker would backdoor into my dad's A12 phone haha, but I sideloaded it from the app I downloaded and packed into a apk file on my A53, with the "file manager plus" app (doing a backup of freeflight and sharing the apk.)
But yea still somehow the app refuses to work and says it requires internet even if it has it.