You're referring to the materials. I include materials for each render pipeline. There are full instructions in the text file in the root MAST folder.

If you're seeing a pink grid, then you're probably using the universal render pipeline. You need to drag the urp shaders onto the grid, eraser, and paint area materials in the fsp/mast/etc folder. The grid is meant to be unclickable. If toggling the grid (G) won't allow it to disappear, then for some reason, MAST cannot find the existing grid GameObject. You can use the script posted here "https://answers.unity.com/questions/613728/how-do-i-remove-a-game-object-that-is-not-visible.html" by Can-Baycay, to delete the grid GameObject. I will be utilizing some of this code in the future to fix this bug. Lastly, MAST is really intended for modular models that have a common shared base size. You can see that the demo scene models are all 1x1x1, 2x1x1, and 2x2x1, all multiples of 1. If you need to use a different size grid, like 0.5 or anything, you can adjust the X/Z and Y grid sizes under the MAST settings tab. If you have any further questions, please reach out to me via Discord at https://discord.gg/eMKJ5U5