Hi Larry and a warm welcome to Mac-Forums.
Normally, with this situation, I would have suggested that the previous owner had not properly cleared their Mac before selling and that their Apple ID was still associated with that Mac - rather than yours.
But, you say you got this direct from Apple, refurbished. In that case, I have to ask you you a few questions, sorry.
What Operating System was on the Mac when you got it? Your header suggests you are trying to upgrade to El Capitan. Is that correct? Either way, you clearly got this Mac some considerable time ago. Date of purchase was 2011; may I assume that your own Apple ID has worked fine up till now???
Nice to know your Mac's specs too.
Sorry to pester you like this, but your question doesn't make sense unless we know these details.
Please post back.
Ian