There's a great book "Chiat/Day - the first twenty years" with a lot of ads for Apple and other brands.
Steve Hayden created the 1984 ad while at Chiat-Day. He later went on to work for Ogilvy, so that's probably where the mis-attribution came from.
What's interesting is that he's the same person who created the Lemmings ad a year later. The 1984 ad resulted in a huge boom in sales. The Lemmings ad did just the opposite. Apple closed a bunch of plants and had a big layoff. Then Jobs left Apple. weird turn of events.
[1] https://en.wikipedia.org/wiki/Steve_Hayden#From_first_jobs_t...
[2] https://www.forbes.com/sites/allenstjohn/2012/02/02/the-supe...
Edit: fixed typos
Looks like Apple switched from Chiat/Day to BBDO in 1986. Around the same time Steve Hayden made the same move... and Steve Hayden didn't move to Ogilvy until 1994.