Re: Installed Battlefield Hardline on PC. Must I update in order to play?

If it says you do. It will ask you to install punkbuster at first set up, if I remember correctly. Been a while. See here if you need any help with that: Help article about issues with punkbuster: https://help.ea.com/en/article/punkbuster-technical-issues/

Use this to reinstall: http://www.evenbalance.com/pbsetup.php

Also I would recommend running Origin as admin and using the plug in with Firefox. Mine doesn't work without the plug in. (And doesn't work with Chrome.) But some people have been able to use it plugin free. 

Post back if you need more help.