Fixed! Go to the fix.
Before you can log in and use the app, you'd need to go through setting up a BTID for this. Instructions on how to do this are included in the email confirmation of your TV order however you can also view this Here.
I hope this helps.
Re: BT sport app
@depechemode1986. You'll receive an automated email asking you to create a BT ONE ID to enable you to use the BT Sport App service. Your PlusNet username and password will not work directly with the app and you'll need to create a BT ONE ID/ password. At the start of this journey it will ask you for your PlusNet username and postcode to verify that you have the service added onto your PlusNet account.
Once you've created the BT ONE ID then you'll receive a notification to verify the ONE ID via email, wait at least a couple of hours before verifying and only verify from the email not the app itself of mybt.com. You should then be able to login to the app using the BT ONE ID and password.