If the hands are importing you do not need to worry about that message - it just means that the hand history folder wasn't detected automatically. As long as you've configured the folder manually and hands are importing that's fine.
The Hud should work, but you will need to be using the latest v3.13.9 Beta version if you're using the download client at Party.
PT3 Download PageCheck the
FAQ: PT3 HUD for solutions to common issues and a link to how to report your problem for further investigation if it doesn't help.