Jesus, stop this nonsense narrative, Mourinho wanted Maguire and/or Alder from Spurs. Utd spoke with Leicester and Spurs, and were told... no. Something you and Mourinho seem incapable of understanding. Utd also bought Sanchez via a player swap worth around £30mil and committed massive wages of what 50mil a season almost on Sanchez. Mourinho made in effect his huge summer purchase last January. If you spend more on wages then you have less available for transfers, if you spend way more on transfers you have less available for wages within the same budget.
So if you ignore his massive spending last Jan and previous windows and ignore that his targets weren't available then sure, Mourinho got absolutely noooo support at all. They didn't buy Fred for £55mil or Dalot for another £20mil, or the ~£30mil more per year for 4 years that Sanchez makes over other comparable players. I would say that either counts as spending £105mil with £30mil prespent on Sanchez wages for the next 3 summers, or £195mil in transfer spending for a manger the board apparently didn't back at all.
Remember how only a few weeks ago Mourinho whined about how Spurs wouldn't sell Kane or Alder to Utd because it's all far more difficult than it used to be, both ignoring that it's true for all clubs (if it was true) and that when Berbatov was bought so easily (the example he used) Spurs finished 11th... and that Spurs have been in the top 4 for what 3 season in a row and thus are in a completely different position.
Mourinho had backing every window, he had backing this window, he spent heavily this window, the club didn't manage to buy the two CBs he wanted which would have increased spending embarrassingly high not because they refused or didn't want to but because after hearing the prices they said no to Mourinho. Not because they were good value and they were being cheap but because the clubs demanded insane money precisely to prevent Utd buying them.
Stop making excuses for MOurinho, though they somehow managed to finish second last year, they frequently played awful football and frankly the quality of the football was getting worse, they were grinding out results sure but they weren't playing well. There is only so often you can grind results while playing badly before you stop being able to grind out results.