If you have lost the device with your authenticator app, and you do not have any of your recovery codes, ask the Observa team to reset your second factor.
Try your recovery codes first. If you still have one, sign in with it — it is faster and it does not need anybody else.
This does not change anything by itself. Someone from the team has to verify your identity first, and after that you still have to set up a new authenticator before the account works again.