On a macbook with a m1 and using unity 6. When I opened the project the island is purple. I know I looked that this a few months ago and the island was the color it was supposed to be. So I dont know if this is a unity 6 issue or a macbook issue. Did the previous guide tutorial last night and it worked just fine.
It has something to do with URP. I made a new project using Built in render pipeline and it fixed the purple issue. I know nothing about URP so idk how to fix that.
To fix this the first thing to do is identify the issue:
So in gaming, since oh a long time, any “Missing Texture” is usually represented by a vile pink purple, sometimes checkered.
The issue here is exactly that, the project may be designed in Standard pipeline, which has different shader graph to that of URP (Universal Render Pipeline), The quickest fix to this is (Looking at screenshot) where on right it says “PolygonMinis” for material, under it “Shader” change that option to “Universal Render Pipeline/Lit”, then re fill the Albedo/Base Colour texture with the texture you require, that or create a new material, drag it onto your object and add the same texture
Hi, Werwin! Yes, it seems like the tutorial you’re working on was built with the Built-In Render Pipeline and not with URP.
It’s ok not knowing about URP yet! The only thing to know is that using the right template with the corresponding render pipeline fixed it. 
Happy learning!
- Kirk / Senior Community Manager