The deal looks like it's going to happen. Not bought directly but, Ugarte will be brought in on loan and contains an obligation to buy. Yes, that seems like the best way if PSG remains firm with their prices because if it were now, Man United would definitely be having a hard time getting the funds.
One of Man United's weak points is the defensive midfielder because they don't have a truly tough figure to carry out that role. Casemiro did play quite well in the previous 2 matches but I doubt if he can continue to be consistent. For this reason, it is hoped that Ugarte will be a solution.
In my opinion, this is not a matter of financial difficulties because if you look at it, the current owner of Man United has the ability to buy at that price. But it seems like they are trying to negotiate according to the price they want. If in the previous season Man United bought players like they were careless, this season they prioritize suitability and look for players who are really needed.
Casemiro has difficulty playing consistently, especially since the competition will last a long time and the other players owned by Man United are completely below quality. Ugarte will be a player who is quite needed by Man United because his presence can provide strength in the middle line as a defensive midfielder.