Consider this example: You and your friends recently started earning money and want to invest your savings. But you don't know how to pick the right stocks, bonds, or gold.
You have another friend who is an experieced investor and manages other's savings. So, you and your friends decide to pool your savings and give it to your friend.
He will manage your money and invest in the right asset classes with his expertise. However, he will charge a fee in exchange for managing your investment.
In real life, AMC is like a friend who takes money from multiple investors to manage and invest in the right opportunities in exchange for a small fee.