He is totally allowed to have these documents just the same as every other President. If you cannot see that this is nothing but a corrupt witch hunt then you are playing for the other side.
I’m mushy middle, I’m no fan of CRT and the great proliferation of social rules bogging us down, but I also think that Trump got played by Leonard Leo and that he is a human being who could do worse than to retire as elder statesman after having single-handedly broken up our elites zombie trade policy that aided the rise if China far quicker than would have otherwise happened. If he kept documents that are still of strategic interest, he shouldn’t have.