Group Icons
Using the Photoshop/Affinity template to make platform/collection icons.
Download Templates Here (Google Drive)
Remember to hide the Game Template folder if you are working with the Group Template folder and vice versa.

The Border Group works exactly the same, just tweak the colors by Ctrl+Double Clicking on it.

The Cover Group is harder to understand, it consists of three parts:

Icon Group
You need to put the icon you want for the console/collection you want (for example Nintendo Switch, Android, Sonic Collection, etc.).

A bounding box should appear as well if you Ctrl+Click on the box at the side of the group name: Remember, everything outside of the bounding box will be hidden.

Dot Grid
Don't touch it, you don't need to edit it, it's just the dot pattern for the background.

Image Group
This group contains a lot of layers, but you only need to edit the Gradient and the Background Image.

Thank you to glpg35 for optimizing these templates and making this guide.