Thanks for your reply.
I feel this is only half of the truth.
Account settings allows to specify "Email" which seems to be what you describe, the Email target address used as default recipient for sending out information from the OBD Car Doctor App.
But there's the second option to "Login" which by default is saying "Not authorized".
When you press the "Authorize" button it allows you to enter your "OBD Car Doctor Personal account ID" and password. When I understand correctly, this is used to transfer statistics out of the OBD Car Doctor App into this website.
When you use "Authorize" to connect to this website, this issues "connection failed" messages when the iPhone + OBD Car Doctor App is not connected to the OBD ELM327 connector on the car. These messages are not related to "Authorize" the App connection to this website, because the App successfully connects and offers to logout.
I'm being very detailed on my findings because I feel that more people my search for this and will hopefully find my post useful.
Again, I think you need to focus on improving the documentation now. Otherwise people my switch to another, better documented App - at least I already thought about this.