I've actually worked for Upwork, when they called themselves ODesk (and I feel like it was another name before that). Anyway, if this is just the first assignment there and you're reluctant to work under those conditions, I'd pull out, with an explanation and apology - not a gripe - and simply walk away from Upwork. Instead, since you're just testing the waters - test them somewhere that you can set the terms, like Constant Content or Fiverr. You'll still face similiar newbie challenges, but at least the gigs you get will feel worth it :-)