Me too having the same issue not matter what user name/e-mail I use I can't seem to login to the software, keeps saying error 3. I am able to login to the webside via my user name and password but this will not work with the software.
I just signed up for premium, downloaded the application onto my macbook air. It won't let me log in. Error code 3. I tried every combination of username or full email. Even changed password. Changing your password requires the current password....... so why can't I log in. This needs to get fixed. Also can't log in on my phone. Do I have to wait to be charged in order to use spotify or something?
I had this exact problem as well. I typically use Facebook to log in to my account. So all I had to do is go to fb.com reset the the password.. Then logged in using the same credentials as Facebook. Seemed to fix this issue!