Mueller Report, even redacted, is damning of Trump and cover-up man Bill Barr. No one can cry "no collusion" anymore.
Based on the report itself, there’s actually ample evidence of collusion.
The report details out how Trump and his campaign knew about the Russian interference effort, actively encouraged it, and would profit from it. They had numerous contacts that allowed everyone to understand that Trump welcomed the help and would reciprocate. Through most of the campaign he was trying to secure a Trump Tower Moscow deal that required Russian government assistance and would be worth hundreds of millions. Even if the smoking gun was never found in a signed document between Trump and Putin, the incentives were obvious. Crucially, Trump repeatedly lied about all these facts.
Clearly President Trump knew that these facts would be devastating politically and could end his presidency. He’s quoted as saying as much in the Report itself. He also could have no confidence they didn’t amount to crimes. And we haven't even learned what Barr has redacted yet.
Regardless, the salient point is that Trump knew the investigation constituted a mortal political threat. He chose to use every power at his disposal to obstruct the investigation.
It’s really that simple.
As a legal matter, you’re not allowed to obstruct or interfere with an investigation at all. For the simpler question of why – why did the President constantly lie, hide evidence and try to derail to investigation – the Report makes that crystal clear.