When I clik on the artist name it says "please configure a Browser in the Settings dialog". But there is nothing like "browser" in the settings dialog (I think it should be under "connection"). I compile fine lastfmplayer, but looking in the source code, there is no browserEdit in settingsdialog_connection.ui. This looks like an upstream bug, because in fact browserEdit is present in what seems to be an old settings.ui. A workaround for this is to set something like "Browser=/usr/bin/firefox" under [general] ~/.config/last.fm/player.ini.
Thanks, as discussed in IRC I added a postinst-einfo note about this!