Trump got into politics by playing the race card against Obama.
The Birther movement that tried to de-legitimize Obama as not born in America was part of that, as was the sly Trump comments that "some say" Obama's birth certificate shows him to be a Muslim.

The Trump family refused to rent properties to African Americans.

When KKK leader David Duke endorsed Trump during the election run, the candidate pretended he didn't know Duke and refused to reject his endorsement.

Actual nazis in full regalia marched in Charlotsville to the tune of Heil Trrump, KKK leader David Duke reminded Trump his followers are White and a Nazi front news outlet thanked Trump for (initially) not denouncing the Nazis who marched wearing Trump golfing outifits.

Yeah, hard to understand why anyone might link racism, neo-nazism and white anger generally to Trump.