Below are the materials I recommend for this project. You are more than welcome to go rogue, just be sure to check your gauge to manage sizing. Some links below are affiliate, meaning I'll make a small commission if you make a purchase, but this is at no cost to you.
The pattern will have you covered on making your front and back panels, but I wanted to show you a quick visual on how to seam them together. I start with the top, and you'll see that the stitches to go through are clear and simple.
The sides are a little more wonky, but just make sure the fabric lines up and go under 2 loops (for strength) on each panel. Insert the pillow once 3 sides are seamed, then seam your final side.
Review basic stitches + skills as needed.
I am quite human, so you may find a note or two here in the future. At the moment, this project has no known errors, or discontinued materials.