I am starting a campaign and building a Goliath character and when I go to select their background I am only given 7 options even though I know there is more in the players handbook which I have access to as a source. I am wondering if there is something I am not selecting correctly or not having access to that would allow me to select Outlander for this character.

You have access to it via content sharing from a campaign? If so - you can only use content from content sharing on a character that is actually inside the campaign. If you're making it in your "My Characters" section then you won't have access to it.
If you are trying to add it to a character that is inside the campaign - ask the person who turned on the content sharing to turn it off and on again. Yea - I know how it sounds - but it refreshes the content sharing table and makes it up to date.

If you meant that you own the book on DNDBeyond yourself - perhaps check to make sure your entitlements are in sync here: https://www.dndbeyond.com/account/marketplace