A have a plethora of problems!

Hello all,

I'm a student working on a project that's due in a couple weeks and I've been working on this for months. I have had a few issues with building the game. But I fixed it by changing the source in "Environment Reflections" to Skybox in every scene and that would build. The build, however, would not work and "Unexpectedly quit" upon opening. Then I tried to build another and got this error

I tried building seperate scenes to narrow down to the scene that was causing this then this happened - https://youtu.be/o2O_7zKRql0

What I'm wanting is - https://youtu.be/pa_Qie2wMVA (Much smoother in real life, no idea why it's lagging so much)

I started trying to find the problem and, it turned out that the post processing behaviour script was causing this. Simply disabling the script fixed it but I wanted the effects so I tried to see which effects were causing this but none of them were - I disabled all the effects but kept the script on the camera active and built but it was still doing what it was doing in video 1.

I believe I have posted all my issues so now I'll post specs.

I'm using a this mac -

I have the post processing stack, standard assests folder, some sort of example scene folder with all it's assests (maybe a component in these are causing errors).

I was using Unity 2017.1 but changed to Unity 5.6.3f1 (after I got build error thinking that would fix it)

Can anyone please help? My future depends on this project haha. Any help would be greatly appreciated.

Just as I was finishing up this post I saw this Error : "Metal: Compute shader has 1024 threads in a threadgroup which is more than the supported max of 512 in this device" this isn't the first time I've seen this and I'm not that technical so I have no idea what this is. Please help!