It's a manu-matic process. If i remember, at some point you would have clicked a link to initiate that process, which would send you email with a document to sign and return back to RokuCo. After accepting your PDF papers, dev.support will flip a switch on your account and then you will start seeing extra menus.
Check your email folders. Couple of years ago the email was coming from "email@example.com", titled "Additional Information Required" - don't know about now. If you got it, follow instructions. If not, ring developer at roku.com for help.
Hi Gil, you need to send your W9 or W-8BEN form (if not in USA) to enrollment [at] roku.com. You might also copy developer [at] roku.com in case the first email somehow doesn't get to where it is supposed to go.