As I have said before, I really don't see the point of this.
I can only assume that the the benefits are to the site somehow and not the writer. I fail to see the point of churning out 50000 words of tripe, that the site freely admits, is purely about the quantity and not the quality.
If people want to write, that's fine, but do it for the love of writing not some weird, irrelevant, arbitrary target set by someone who plainly has no interest in the work submitted.
All this seems to be is a wasteful distraction from what could be productive work for a real attempt at a novel.
Even if you only achieve 100 words towards your ultimate goal of a publishable novel, it's a far better way of using the time rather than this farce.
It seems to me you could write out 5000 lines of :-
I must not waste my time on stupid writing exercises.
Add a title and a bit of background -
Bill a naughty schoolboy went to school one day and was naughty. The teacher made him do hard writing work as a punishment.
Bill started to write out what the teacher said he must do
Then just cut and paste the quote above.
And they would still send you an acknowledgment for your fine effort.