This is the official Hot Start CL650 Substance Painter paintkit file. It contains several liveries within the "Paint" folder" on each UDIM. You are free to add to whatever materials or masks to those layers as you wish. There are other folders that are set as default textures, with materials included. These are the correct materials for the areas they are assigned to, but you are free to alter those as you wish.
As usual, if you plan on changing anything, keep the original smart material, and create a copy of the folder in the layers palette. This will save frustration if you wish to return to the original materials.
Please read the included readme file.