You have multiple challenges baked into one here:
- Get an enemy to chase the player
- Get an enemy to respect the other objects in your scene
- Have the enemy find a valid path around the object
The first two are quite simple to get working, the third requires a more complex solution, either using ray-casting for very simple scenarios, or actual path-finding such as A* maps or similar. In this latter case, implementing it is quire a lot more tricky.
Either way, I would recommend you do some more searching on the first two, there are plenty of solutions to this problem already. I did a quick search and found these:
chase player: https://answers.unity.com/questions/274809/how-to-make-enemy-chase-player-basic-ai.html
for changing direction: https://answers.unity.com/questions/284206/change-direction-on-collision-problem-1.html
There are also a lot of basic tutorials on these on youtube. Either way, you can't simply copy paste a solution, as you will need to understand what is unique to your game world.