Converting Object Reference to another Object Reference

So I’m a newbie at Unreal Engine and I’m trying to integrate this into my project. Here’s what I’ve done:

  1. Copied all the CPP files, then compiled them.
  2. Created the necessary Blueprints inheriting from those CPP files.
  3. Copied all widgets in UI from that project to mine using File Explorer.
  4. Lastly, I’ve tried following the HUD Blueprint when I ran into a problem.

As you can see from above, I cannot convert my (Picture B) Player Controller Object Reference like it does in Picture A.

What should I do? Thank you so much in advance.