"When they came to Marah, they could not drink the water of Marah because it was bitter; therefore it was named Marah. And the people grumbled against Moses, saying, 'What shall we drink?' And he cried to the LORD, and the LORD showed him a log, and he threw it into the water, and the water became sweet. There the LORD made for them a statute and a rule, and there he tested them..." - Exodus 15:23-25 ESV
Did God bring them to Marah? Yes.
The tree represents the cross.
"...saying, 'If you will diligently listen to the voice of the LORD your God, and do that which is right in his eyes, and give ear to his commandments and keep all his statutes, I will put none of the diseases on you that I put on the Egyptians, for I am the LORD, your healer.' Then they came to Elim, where there were twelve springs of water and seventy palm trees, and they encamped there by the water." - Exodus 15:26-27 ESV
Israel had national mandates but we have grace.
"For sin will have no dominion over you, since you are not under law but under grace." - Romans 6:14 ESV
We have a tree to cast into the bitter waters.
Sober thinking has a tree for the bitter places. Then we move on to Elim. Before the tree goes in the water Elim doesn't look possible but both places are in God's plan.
We have all been damaged along the way but the LORD (Yahweh - Strong's H3068) is our healer. Eygpt doesn't have him. Eygpt resists Him in futility because He Is irresistible. That tree is a sure remedy for all who take it and cast it into their situation.
There are theologies that claim that if you have enough faith you will never get to Marah but that isn't how it is. Marah and Elim are both destinations we will visit. The tree is what we look for when we get there. The tree is what we prescribe for those who have nothing but bitterness to drink.