He’s talking about the downforce created by the spoiler............at 160-170 mph...........
It would be nice if the OP did some research before posting.
Obviously. But the author either did a real crappy and fast cut/paste job from another article or a press release OR he doesn't that a clue about anything automotive. It's really hard to tell these days.
I looked at the Ford press release and there is nothing about downforce. In "Inside EVs" I found Mustang Mach-E 1400: Exclusive Chat With Ford's Global Director Of Motorsports which says "Airflow management was also a challenge because they needed to factor in the cooling and aerodynamics, but also to create the tremendous 2,300 lb downforce the team wanted to achieve." But it doesn't say what speed is required to generate this downforce. It's probably in the 160-170 mph range you suggested.
There are some great shop pictures at the "Inside EVs" link, too.
Then I found a Malaysian site with an article Ford Mustang Mach-E 1400 prototype – seven electric motors, 1,400 hp; 1,044 kg of downforce at 256 km/h which provides all the specs. That's 2,300 lbf of downforce (note pound-force, not pound) at 160 mph (the same speed you were saying).