Since the Super Bowl is between the New England Patriots and Los Angeles Rams, this deal will apply to either Boston or Los Angeles (even though the Patriots technically play in Foxborough, MA). You'll also have to be signed up as an Uber Rewards member. If you live in one of those cities and haven't signed up, the good news is that it's an easy and free process. And just to be entirely clear, you must be in the corresponding team's city for it to work.
The "free" ride is only free if it's under $50, too. Granted, not too many rides you take in your own city are likely to exceed this high bar, but it's not impossible, especially in a city as large as Los Angeles, so it's good to know the "free" ceiling. Uber is branding these free rides an "Unhappy Hour," though it might be more like an unhappy night, or even a week, for the city on the losing side of this game.
We do admire the idea of getting potentially drunk fans home safe after the game, so hopefully bar-goers and Super Bowl party attendees make good use of the deal. Winners will most likely want to stay out and celebrate, so the ride might be lost entirely on them as they stick around to watch the Lombardi Trophy get presented.