(emphasis added).[ . . . ]be very careful not to confuse "deferring to an authority on the issue" with the appeal to authority fallacy. Remember, a fallacy is an error in reasoning. Dismissing the council [sic] of legitimate experts and authorities turns good skepticism into denialism. The appeal to authority is a fallacy in argumentation, but deferring to an authority is a reliable heuristic that we all use virtually every day on issues of relatively little importance. There is always a chance that any authority can be wrong, that’s why the critical thinker accepts facts provisionally. It is not at all unreasonable (or an error in reasoning) to accept information as provisionally true by credible authorities.
Your source agrees with my college textbook.
Even if these weird things called "books" are too hard for you, you should at least try harder to read and understand your own internet source, Diaperboy.