If you stumbled upon issues with your College Board account that are preventing you from linking it to Khan Academy - or are having any problems that seem to be out of Khan Academy purview - you can always reach out to the College Board support team and they will be more than happy to help you.
Their official website is https://www.collegeboard.org/ and their support channels are:
- College Board Account Help Center - in which you can find several articles that deal with account issues in College Board
- Phone number: 866-315-6068
- Contact form for you to send a message directly to College Board