The GCs are shipped separately from their 'activation code' for security purposes. They may arrive up to a few days after the GCs. If you don't get your activation code or they are delayed and you are in a hurry:
Call 1-866-357-7391, press 3 to speak to a CSR.
(How To Activate Staples Visa GCs Without the Activation code.
http://travelwithgrant.com/2014/05/12/how-to-activate-200-visa-gift-cards-from-staples-com-without-the-activation-codes/ )
Recently they've sometimes been emailing activation codes. Also check your spam folder.
PSA: VISA rebate cards may be an issue if used to purchase VCG's from Staples online. It seems to be YMMV. With larger orders more likely to invite scrutiny.
In store they work fine.