Unable to create AAC version despite following all steps.

I have followed all the steps required to create my own ringtone from a song. However, I am unable to click "create AAC version" despite being able to see the button. It remains grey instead of black.

So, I decided to convert my song to AAC via a website. And when I tried to drag it into itunes, I was told that it cannot be copied over because the phone cannot play such a file. Seeing as the step after create an AAC version was to change the extension m4a to m4r (how did AAC become m4a in the first place?), I decided to convert my song to m4a instead and then changed it to m4r. After which I successfully dragged the m4r file into itunes but itunes refuse to update itself with the ringtone. Meaning that it has the loading circle next to it. Thus, I cannot sync it to my phone.

Please advice. Thanks.

*The "insert image" button does not seem to work so I can't attach any picture. 😐