"Sharing" content that is behind a paywall

that is exactly what happens, the credentials are confidential and are remembered only on a per app. If you want to open such page in @Voice, once you see or hear the login text page in @Voice, press the "Reload or clear" button (circular arrows) on top, then pres "Load from browser..." on the little menu that appears. The page opens in internal to @Voice browser window. Enter user name and password there, mark an option to "remember me" if possible. Then press the loudspeaker icon at bottom right and you will get your article normally. Next time you share a web page from the same web site to @Voice, if will already have your password and open it nromally.
 
Greg