I have installed Zenphoto as a one-click install via my shared hosting and have no FTP access. I have three large albums which i'd like to download, preferably without wget hacks. Is there a way to download albums as zip files from the admin interface without installing extra plugins?
You don't need a plugin but you need to modify the theme used with the needed function printAlbumZip(). There is a tab on the Zenphoto backend to edit theme files. Read the theming tutorial before trying.
Btw, we don't support and recommend one click installs for these and other reasons.
EDIT: My fault I missread the "from admin backend". Sorry you are out of luck, there is no such feature as any proper webspace has ftp access.