I see. I figured that I have to use some other account. (3rd account already - one for the shop, one for the cloud data, and one for the forums)
Unfortunately I haven't written down my credentials for the cloud data account. In order to find what email did I use for that I started the app on the old phone but it doesnt say what's the mail, it just gives me the possibility to change the mail.
In the end I remembered what is the correct email address and I reset its password and I logged in the app.
However - my proposition for improvement is the app to show somewhere which mail is used to log in. Some another forgetful client (as myself) not remembering the correct email addres could see what is the correct mail and help himself without issuing tickets and writing here.
Thanks