Hello! I can not sell photos through Adobe Stock. Fotolia and Adobe Stock accounts have been synced. But "Access Denied You do not meet the age requirements for this specific service" appears.
I am over 18 years old for a long time. 🙂
My guess is that you entered the wrong year of birth when you set up the account. You cannot change this yourself (I can't see a place to even check it), so contact Adobe Customer Service.
Warning, scammers may contact you privately pretending to be Adobe staff. Adobe will never send you a private message asking you to email an account that isn't @adobe.com, or use Skype. These scammers want your credit cards, your personal info, your money and control of your computer, please take care.