This is Infinity War Captain America, with his twin vibranium shields at hand.
Okoye stands with three of her best Dora against the super-soldier.
Who wins?
Cap wins, in my book Cap would defeat Killmonger, even with the Black Panther herb power.
I do not agree that Killmonger's skill equals Cap's - he's just better than T'Challa, which is to say that he is an exceptionally skilled fighter, but Cap is another story. We've only seen Cap briefly face off against T'Challa, and to be honest he wasn't trying to take him down, he was just trying to get past him.
As skilfull as the DM are, Cap is still much, much, much faster, stronger and tougher than the average human (low level superhuman - although strong enough to briefly hold off Thanos).
Cap is a master of fighting multiple opponents at once, I feel like he was somewhat undersold in Infinity War, but his feats in Civil War, Winter Soldiers, Avengers and Age of Ultron speak for themselves.
The DM held down Killmonger briefly, but I'm confident Cap would find a way to deal with them.
If Cap had his normal vibranium shield it wouldn't even be close.