If you choose the 'Sign up with Facebook' login option, you're logging in directly with Facebook.
Plann does not save any of your Facebook/Instagram login details or ask you for any permissions that involve posting or commenting on your behalf.
At the ‘Log in to Facebook’ page, simply enter your email address or phone number along with your password.
You will then be taken directly to Facebook's login screen:
Forgotten your Facebook Account Details?
If you’ve forgotten the details of your Facebook account, you can click the ‘Forgotten account’ link and follow the steps Facebook issues to recover your account.
Important Note: If you select ‘Create New Account’ at this screen, you will be creating an entirely new Facebook page. If you wish to connect to your existing Facebook account, simply enter your email address or phone number, your password and select ‘Log in’.