I agree that God did not make Adam sin, he had a free will. Where the problem comes in is that under Calvinist determinism and God ordaining/decreeing all things {WCF/LBCF} then that means Adam could only do what God had determined for him to do, as with all sin that we see.
That is a valid point. If you read Edwards or any discussion of this that goes beyond calling each other names you find this argument. I tend to think that God created Adam with the primary wish that Adam not sin. But the problem for my argument is that God is all knowing and all powerful and Adam did sin, yet God could have prevented it. One Calvinist argument is that God has two wills. He honestly did not want Adam to sin. But he also wanted to give Adam a truly free will. Being God, he knew Adam would sin (he knows everything) and thus the plan of the Fall, sending Christ, redeeming a multitude of people was already in place. This was God's sovereign will. Now, I think this is a fairly weak argument. But, and this is very important - for all of us on here who believe God is all knowing and all powerful we are left with the fact that Adam did sin. God either knew of it beforehand and allowed it anyway, or it took him by surprise and he reacted with the plan of redemption. I would make 2 points:
No non-Calvinist has been able to come up with a better explanation for God knowing something and allowing it to happen and letting it happen and not being somehow thought to "ordain" it.
Also, some Calvinists do go too far I think in describing events as being directly attributable to God. For instance, we live in a fallen world, of our own making. We die and have accidents. But if a plane crashes I don't think it's correct to automatically say "God crashed the plane". Some do, and I don't agree with them.