The easy way to know what’s in the Mueller Report is to read the Mueller Report. It’s completely public.
Probably the closest thing to confirmed is that Roger Stone was in contact with WikiLeaks and was coordinating the release of materials with them, and that Trump was aware of this. You effectively have to assume that Trump and everyone that he knows was stupid enough to believe that WikiLeaks is not being run by Russia, to forgive them for that. But, even if we ignore the Russia topic and just think in terms of what job Trump was running for then this episode should immediately have rendered him unfit for office.
If you’re running to be the head of national security and you’re creating a debt to a group whose whole existence is set up to try and collect and publicize top secret materials; that’s like running for fire chief while working with an arsonist to burn down your opponent’s house. Russian involvement is sort of irrelevant to the equation. Just saying, “I love WikiLeaks” or “You’d have to be stupid to not accept information from a foreign intelligence service, against your political opponent”, are both blunt and unambiguous admissions of being unfit for office.
Manafort was sending information to Russian sources, had foreign debts, like 15 cell phones, and three passports from different countries. The guy genuinely seems to have been an agent of someone or at least deeply compromised and living a life of crime. But, on all of this, there’s no particular indication that Trump was aware of this and it’s not clear what Manafort’s angle was.
Where Trump becomes guilty on this one is that he continued to work with and chat with Manafort even after his own appointees all agreed that the guy was stinkier than a 3 month dead skunk’s anal gland. He pardoned the guy and, from some moves that Manafort made, it seems like that may have been a trade for silence.
In similar respect, Mueller showed that Flynn was compromised - mostly by Turkey, but possibly others - and Trump’s appointees, Rosenatein and Barr, both confirmed that the Intel was damning. And, again, Trump continued to hang out with Flynn - including plotting the false electors scheme, several years later - and pardoning him of all crimes.
While Mueller did not prosecute Steve Bannon, he does note the destruction of evidence by Bannon and George Nader relating to a meeting with Alfa Bank and the UAE. Again, Trump continued to work with Bannon and, later, pardoned him for fraud against MAGA voters - as prosecuted by his own appointees.
On the side of Russia, we have people in Trump’s territory sending information to Russia and different people getting stuff out of Russia, but it’s not clear if those are related. The bigger concern is that there was a lot of evidence destroyed, witness tampering, and provable lies between the whole Trump group, when questions about Russia were asked. That’s not conclusive, but it should be deeply concerning to anyone who is, again, of the sort to think that it would be dumb to hire a fire chief who sure seems to hang out with a lot of people that like to commit arson.
But, throwing away Russia and assuming that everyone’s innocent in that angle - maybe Russia just tricked Trump’s people into doing stupid things - you still have to be concerned that Trump’s friends are criminals, all easily compromised, and that he has no excuse to not know this given that it’s his own people that proved it to him. If he continued to hang out with those folks then you have to assume that he’s equally criminal or that he’s just an idiot of the first degree.
Personally, I don’t see how you argue the first when you look at events like how Trump introduced Manafort to Stephen Calk. How would Manafort know that he could safely commit back fraud with Calk so quickly, unless he knew the sort of people that Trump hangs out with?
The media and Democrats always seem to be strangely myopic and miss the bigger issues. How do we know that Trump knew he lost the election? Well, did he ever do anything to shut down the Deep State, after they spied on Carter Page? Or did he approve the continuation of the FBI’s post-9/11 wiretap abilities and raise their budget? Has he ever admitted the he doesn’t believe in the Deep State theory? Did he ever say that he thought the Democrats would steal the election, prior to election day? Well then, did he implement any of the measures towards securing elections that were proposed during his time in office?
If you have questions about what a person believes, look at what they do. That’s how you know what they believe.