There’s a lot of people angry about this. People are accusing Mihailovic of being a collaborator because of Chetnik units committing atrocities, and his lack of doing anything about it.
I think people are too idealistic about the realities of World War II, the Chetniks weren’t full blown collaborators like the Ustasha or Nedic’s puppet government.
Well, Tito (i.e. his lieutenants) also collaborated with Nazis albeit nothing really came out of their discussions.
That said, the primary point is that most people do not understand that there was a civil war going on in that region within a broader (larger) war - of course that broader war being WWII.