Help with new red japanese maple – Reddit Post

I got this beautiful red japanese maple tree as a present from my parents, I planted him 5 days ago, but his leaves started to crumble and fall off, mostly on his left side. We don’t have a good soil, it contains a lot of clay, so we added a bag of quality soil around the roots. I did not manage to untangle the roots, they were very bound from the container we got him in, so I planted it as is. Please, I really really need him to live, what can I do to save him? Is he dying or is this just normal autumn behaviour?