Does Don say "I am a white supremacist"? No, obviously not. Does Don even think he's a white supremacist? Probably not. Do so many of his racist comments & policies expose him as one? Yes.
Don has absolutely, 100% said the words that he "condemn[s] white supremacy". No denying that. It feels empty though—like a salesman telling you what you want to hear to seal the deal—when he goes on to say something else racist or derogatory toward brown & black immigrants (or citizens or anyone else, which he does a lot). Has he ever said anything negative about immigrants ("illegal" or otherwise) from prodominantly white countries? No. He usually says those are the kind of immigrants we want.
The love that blatant or avowed white supremacist groups have for him also shows that even if he doesn't think he's a white supremacist, they do. Do you think they would support him to this extent if he regularly and consistently condemned them and their support?