"The office is not near the train station."
It shouldn't be mandatory. You should be able to substitute に instead, unless the lesson calls for から。'The office is not close from the station' would be a more accurate (if unnatural-sounding) translation.
wouldn't えきはかいしゃからちかくないですbe equally correct? "(regarding) the office, from the train station it is not close" vs "(regarding) the train station, from the office it is not close"... I mean, I might change up which I used depending on my starting point (or the starting point implied by the context) but... there is no context here. edit: I know the glosses are clunky, hopefully you get what I mean
no, because the main subject is the office かいしゃ and not the station えき, in short you have said the opposite. I hope this may help you.
I think that the unwritten context is telling someone how difficult or easy it is to reach the office from the train station, i.e. how much time or effort it takes to 'get to work' (direction of movement).
If the focus was on explaining how much time/effort it takes to return home from work, your sentence would be more appropriate.
I'm not saying that you are wrong, per se. I just think that a lot of context is left out of the sentence and Duo wants us to fill in the gaps in a narrowly-defined manner.