Sounds like Nine Now doesn't support WebOS fully. The browser is built into WebOS and I guess they will update if they think they need to. In the meantime I dare say they will suggest that you get Nine Now made compatible with WebOS which is what they usually come up with. They're just not interested.
As far as I'm aware, there is no native pdf reader on the LG Smart TV WebOs. If the app is not in the LG content store then likely it is not supported.