Newly made ringtone won't sync to iPhone

I just bought an iPhone and decided to try to make some ringtones. I've only made one and stopped there because it didn't work. I successfully downoladed the song, went in to the ringtone creator, and created a ringtone and clicked buy. Eveything seemed to be confirmed but when i went to transfer it my iphone, it said i couldn't because this computer (my mac that i used to create it) wasn't authorized on that account. How do i fix this?