When entering a Facebook page as an Aggregation Term, you may receive a warning that this page's content is restricted.
In this case, you won't be able to aggregate content from this page unless you have connected a Facebook User and/or Facebook Page Token.
WHAT MAKES A PAGE RESTRICTED?
Generally, Facebook restricts external access to a page if it:
Has an age restriction imposed
Has a geographic restriction imposed
Has not yet been 'published'
If you manage the Facebook page, you may be able remove these restrictions within Facebook.