You can't download via the click to install. You need the actual deb file.

go to http://www.fbreader.org/downloads.php (got to via the homepage link on the fbreader entry on downloads.maemo.org)
and from there you follow the obvious path to the offline installation:

http://www.fbreader.org/maemo/maemo2.php#maemo2.offline

(I note that a browser that shows you the URL for a link when you mouse over it is very useful - you can see if you have a link to a deb or to something else.)

Zebee