Both phones (including the free one) must first be purchased using an Equipment Installment Plan, and taxes and any down payments must be made on both units. A new line of service needs to be opened, and one of the Galaxy S7 or Galaxy S7 edge handsets must be purchased for that line. The memo also lists some thing about a mail-in rebate with a pre-paid Mastercard involved, and there is a limit of two free phones.
If you're thinking about adding a new line to your T-Mobile account, and one of Sammy's new handsets is in your sights, you just might want to wait a few days for this deal to be in effect before you proceed. Otherwise, you might miss out on a free Galaxy S7 or Galaxy S7 edge.