To be fair Sam and Bucky were both kind of unnecessarily hostile towards him for being Cap even if he was way out of his depth and not prepared to grapple with Steve's legacy, but he still tried to do what he felt was his job even if he wasn't qualified for it...at least in the way of being Captain America.
That's always been the appeal of Zemo, like how he managed to subvert and wreck the Avengers with his Masters of Evil during Under Siege.And I think that's his appeal. He may be sneaky and manipulative, but he doesn't pretend to be anything that he isn't. He knows his limits (admitting in CW that he knew there was no way he could take the Avengers head on) and does his best to work around them. In a way, that makes him an even better archenemy for Walker than Rogers.
I wish we had gotten more of Steve vs Zemo than, like, the five second conversation they had in Civil War.