Forge Networking Remastered iOS Build Error

I'm trying to add multiplayer to my iOS game using the Forge Networking Remastered Unity Package (downloaded from the Asset store).

When I run Play Mode everything works fine. When I build the project into Xcode I get the following error:

      "_ForgeClose", referenced from:
      _TCPClientWebsockets_ForgeClose_m926061065 in Bulk_BeardedManStudios_0.o
      (maybe you meant: _TCPClientWebsockets_ForgeClose_m926061065)
      
      "_ForgeWrite", referenced from:
      _TCPClientWebsockets_ForgeWrite_m1361172110 in Bulk_BeardedManStudios_0.o
      (maybe you meant: _TCPClientWebsockets_ForgeWrite_m1361172110)
      
      "_ForgeConnect", referenced from:
      _TCPClientWebsockets_ForgeConnect_m503395061 in Bulk_BeardedManStudios_0.o
      (maybe you meant: _TCPClientWebsockets_ForgeConnect_m503395061)
      
      ld: symbol(s) not found for architecture arm64
      
      clang: error: linker command failed with exit code 1 (use -v to see invocation)

In my Unity Player Settings, I have Scripting Backend set to IL2CPP & Architecture set to Universal. I'm building for iOS 10.0

I'm using:

macOS Sierra 10.12.6

Unity 5.6.1f1

XCode 9.0

Any thoughts on how I can make this work?

Thanks.