It seems like there is a bug on the demo scene for pun mutiplayer with ufps 2. It was noted this bug doesn't occur with UCC. Let me know if i can get feedback on this.
What error are you getting? I just tested it and was able to play UFPS 2 and the add-on successfully. Make sure you take a look at the docs for getting started:
Importing Before you import the PUN Multiplayer Add-On ensure that you have first imported: Any of the Opsive Character Controllers. PUN. Demo Scene The PUN . . .