Basic Setup

First things first: you'll need to download and install Northstar.

1. Download the latest version from the releases page
2. Copy all the files in the newly downloaded zip folder to your Titanfall folder
   For Steam - Right click Titanfall 2 > Open Properties > Click Local Files > Click Browse
   For Origin - Click Titanfall 2 in the Library > Click the gear icon > Click Game Properties
3. Launch NorthstarLauncher.exe to start Northstar

Additional Stuff
Since Northstar doesn't launch directly through Origin, any startup arguments provided in origin won't transfer over, you'll need to add them to the file ns_startup_args.txt, which should be in the same folder as you extracted the Northstar files to.

If Northstar doesn't appear to be installed, or you have issues entering the lobby, try running vanilla files, I can't personally say what VPK mods could cause issues with Northstar at the moment, so it'd probably be easiest just to try running unmodded.