I'm having the exact same issue. My first payment is due since moving to my new flat and I can't access my account online to sort payment. I've tried the app but that keeps telling me that my password is wrong, which I have reset. I can login online to see the "your account is still being set up" but the app still refuses to let me in.
I saw this message online when I first got in touch in October, and it hasn't been solved since... Bit concerning for a new customer!
For the second weekend in a row I have been unable to log into my account. It tells me that the account has not been set up when it had been and I had entered my meter readings. Today it tells me my login is wrong which it wasn't. Changed the password following the reset procedure and I am still unable to log into my account but have been able to access the Community page. I was moved over to Scottish Power when Extra Energy failed and so far I have been disatisfied with Scotish Power and their complete lack of communication. If this keeps up I shall be complaining to the appropriate authority.
I am now 2 years down the line with SP and STILL cannot log in. Still told " My account is not yet up and running please try later" I ask you 2 years. Not good enough. Still have to phone them to pay a bill, then wait for the return phone call. Really disappointedin this service.