Annoyingly you can't add an album as a whole to an existing Playlist from within the Android App. You can individually of course, but not in multiple.
I'm not sure this functionality has been available in app for a long time, the only way to manage it 'en masse' is by using the desktop/web player to select & drag multiple tracks from the album view into a playlist.
Please use the search feature before posting a problem/bug/idea. What's a Spotify Rock Star, and how do I become one? Using Spotify Since March 10th 2009 Twitter: @mechanimal82