go to a book like
https://en.wikipedia.org/wiki/Wikipedia:Books/Derivatives. the mobile
skin again is broken and the download link is crippled. if one is
lucky to hit the zim download link anyway, it switches over to a
non-mobile link to generate the book. it really seems to generate the
book, and displays a link. clicking it then downloads a 6.5 mb big
"index.php" and says "failed".
(tested on android 4.1, standard browser, i.e. chrome)