I just took a look at my account too and I see it available there for download. In fact it appears in my list 4 times and there are 20 downloads available on each one of them.... :\
Just to let you know, I've not yet received any email notification yet either. That said, I am downloading it now.
Edit: I just noticed that the page for part 10 in the gamestore indicates that the file is 11.58MB, but the download I just did was only around 7.2MB. Does anyone know if this is correct? I seem to recall things like separate map files in some of the previous chapters.