Try this out, go into Safari and make sure you are logged into your FB account from the FB site directly. If you've already done that, clear cache from Safari and try again. When you hit connect in the game it should sign you into that account.
If you were playing directly from Facebook before then your progress is synced automatically. If it was a tablet your were playing before then as long as you actively connected your game to Facebook, your progress will be saved and synced to it. If you did, when you reconnect to that account in the game from any device,…
Might want to switch your phone off and on again, looks like it's been resolved: https://care.king.com/en/candy-crush-saga/candy-crush-saga-keep-asking-up-to-update-but-i-have-already-gotten-the-newest-version
As long as you actively connected your game to either Facebook or Kingdom, your progress will be saved and synced to it. If you did, when you reconnect to that account in the game again, the progress from the point where it was last synced will come up.
Might want to switch your phone off and on again, looks like it's been resolved: https://care.king.com/en/candy-crush-saga/candy-crush-saga-keep-asking-up-to-update-but-i-have-already-gotten-the-newest-version