PARIS, August 6- Paris Saint-Germain are confident Angel di Maria can be the man to help them conquer Europe after completing the signing of the Argentina winger on Thursday. The 27-year-old penned a four-year deal at the Parc des Princes after PSG agreed to pay Manchester United 63 million euros (£44.3m; $68.9m) to make him the second most expensive signing in French football history.