Found it! The additional content, I mean. Found the same version with working in-app download of said content on a chinese site (no virus).. So it IS possible..

Thanks for the info. Any chance of a link? Cheers.

Lost the tab/webpage, but still got the Mediafire link (it`s v2.11.3, but who cares? We have the content :)
https://www.mediafire.com/file/l6ew3wjbzw6kih6/Star_Walk_2_2.11.3.apk/file

I TAKE IT BACK!
I relied on my AV, but Virustotal detects it (as Ad-ware):
https://www.virustotal.com/gui/file/8850f9ab648cc51d6249739c80e78fe1a4893c9bf9fd7d3290c5161450ef6d68
That explains outgoing connections to sdk.byfen.com (which I block) :(