Thank you. It does not work.
I do not know what kind of router my school uses: a wire comes through the wall, and it works. But I did try your suggestion, and connected using my mobile hotspot. It does not pass the 995KB.
I also tried vallderrama1's suggestion of canceling and restarting the download, even though I think that's another variant of using terminal to get to whatever appstore folder that is and deleting it, trying again, and I've tried that four times.
I've signed in and out of the store like atrenqua has.
Worldshare's guess that we-with-problems have systems too old or full or unprepared for Mavericks does not apply to my case. This computer is young and clean and not full.
I have tried every single suggestion multiple times. There is no progress.
There is a change, however. I used to not see Mavericks on the "purchases" tab, and now I do - with a failure message: "an error has occurred".
Again - I am not getting a little bit to download at a time, and then failure after a spell. I can download 995kb perfectly well, and all attempts beyond that are automatic, immediate "error has occurred".
I've pretty much given up, except I do need this to do my job. My opinion of Apple hasn't been this low since 1994. Pretty frustrating.
I do appreciate your suggestions.