Can't find "Non US Person" tab when filing out Tax Forms for Contributors

I had contributed an article, but I couldn't finish setting up my payment method. Under the tax form step, it says "If you are not a US person, select the "NON US PERSON"  tab and follow the instructions there," but I can't see that tab on my web page. I'm not a US person, so I couldn't fill out the W9 form either. Can anyone help me with this problem? Thank you!