Impossible de se connecter via fb

You shouuld not subscribe via alternate signing methods. 

If you have more than one email address in your Adobe ID account user profile, the Adobe ID that you registered with your current active subscription is the primary email address associated with the active subscription. That is the email address that should be using to sign-in to activate or unlock a service in the Acrobat Reader mobile app.

Try signing in via web browser here: https://account.adobe.com/profile

Identify your primary email address. See if that email address is different from what you're trying to use.

Once you've registered successfully you should be able to sign-in with alternate signing methods(i.e. facebook, Google, etc. )