What about the word order here?
I had the same question.
Why Ősszel, not Ősszen, like in nyaron?
Ősszel, télen, tavasszal, nyáron, it's just the way it is. (& the analogous conjugation would be őszön, not ősszen.)
Duolingo goes on and on about good English.... We would not use the present continuous in this sentence. We would say Peter is not working THIS autumn , or Peter DOES NOT WORK in autumn