How to use the texture sheets provided in asset packs?

So I am trying to create a new title screen for my educational learning project for my first ever game, and I am stumped at the part of applying textures to items that require more complex coloring schemes and designs, for those clothes and towels, they just required me clicking the + sign to find a new material and I found solid colors that looked good (couldn’t even find the orange for the orange jumpsuits that supposedly come with this package.. maybe its in one of those texture sheets) but after clicking and previewing every possible already-ready material, none of them matches what those toothpastes and soaps and deodorants are supposed to look like according to the asset pack listing, and upon clicking the item and viewing the inspector I see the preset material is directed towards one of these sheets with a boatload of colors to it, so theres my question is how to use these?

Also is this the proper way to assign materials to items, how I described I did for the towel and clothing in the picture? Is there a different way for items that will be moving/animated?

I figured the only way to do what I am asking is manually doing it so I proceeded to do that and now I really don’t think I will be able to figure this part out by myself considering all the factors it’s got to do with it possibly haha, so I took the image I needed out of the texture sheet, I kept its transparent background and everything, saved it as a new image, imported it into my Main Menu Folder in my project which is the folder that contains all things related to the Main Menu Scene for my project, created a new material and applied this picture to the base map. I tried countless times reimporting it as new types and whatnot and just cant figure out why the material isnt showing a proper puddle rather than just a giant unrealistic rectangle!

If you want to use textures in an an atlas like this, you’d need to create a UV mapping in whatever modelling package you use to create the models, whether that is Probuilder, Blender, or whatever. The Unity editor doesn’t have any built-in facility to edit this type of data.

Thank you for the response. This will help for future custom asset building, but what fixed this issue was the fact that I was using the Universal Rendering Pipeline for my project instead of Unity’s built-in pipeline which I assume is what the asset pack was compiled together with or however that works, because once I started a new project with the built-in pipeline and reimported my asset pack, every asset immediately had full color scheme and design, puddles were puddles instead of squares, prisoners had jumpsuits instead of naked, etc.

Much more detail in those toothpastes, soaps, and all that, and the orange color magically appeared to exist when I transferred project styles lol here is how it looks now, making a little shower scene with animated prisoners in it for the title menu screen

UV mapping should work exactly the same in URP and built-in, so if you set-up an atlas in built-in, it should still work in URP. If you’re seeing different parts of the texture mapping to different geometry when you switch, then I don’t know why that would be. Maybe you had a custom built-in shader with a vertex function that manipulated the UVs or something like that?