As an Ajax fan for over 20 years I can safely say forget about him coming this season. Sure everyone has a number but it's not a number Glazers are going to pay and more importantly he has a realistic shot of getting far, potentially final CL. 12/12 pts only 2 goals conceded (1 pen 1 unlucky grabble) in a group where we were certainly not favourites.
Besides the above Im not sure United is a good match for him. He plays very structured and disciplined and demands 100% obedience from his players. There's a popular video (I can't link media but its in dutch anyway) where he yells at ex Ajax player Noa Lang from the side of the pitch saying something like Shut your mouth and listen, do as I say. This is our match not your match. Ironically Noa left Ajax because he did not get the game time + contract + starting 11 he wanted which came from him being young, just came from Ajax second team a few months prior, and him being a diva and having an attitude. What I'm saying is, I'm not sure how this would work with the likes of Ronaldo, Pogba etc. The only way I would see him even coming to United is if he gets full mandate to implement his style of play and demand things like his attacking players to put in their defensive chores everytime, and if they don't, bench them or sell them.