People acting like this means 72.6 mil, while previous transfers for other players, the club get 100% of the price listed... they just don't understand that not every club releases this information.
Solidarity subsidy means any club involved in the training of a player receives compensation for any future sale of the player. So, in this case Le Havre and ManU. It's a maximum of 5% combined to all clubs involved in his training. For each year he was at a club from 12-18 the training club gets 0.25% of his transfer fee... For each year between 18-23 they get 0.5%...
It's a often overlooked and forgotten revenue stream for clubs.
Auxiliary expenses probably include Raiola's fee, and other such fees. It's hard to say what's in there. Most football transfers have around 10% or more going to agent + player. And then I am sure there are other fees. (I recall a study published by FIFA showing 28% of transfer fees were going to agents + third parties, that was back in 2013)
It's kind of amusing that people think Napoli actually gets every penny of the 90M we paid for Higuain, or Tottenham got every penny of the 90-100M paid for Bale. And so on. They all have solidarity mechanism and auxiliary expenses to pay on football transfers.