The red square is the null object used to control the white square and the lines. Only the white square and the lines will be visible in the render. In the Map – Clean composition, the top layer is “Square”, expand it and under Contents > Rectange 1 > Stroke 1, you can adjust the stroke width.

In the Assets folder in the project, open the “circle” composition. Inside you will find two layers. Change those two blue to whatever color you want. One layer is the circle’s border, and the other is the fill. You could also apply an adjustment layer above them and apply the Hue/Saturation effect to it. I found that setting the master hue to 150 produces a very nice red. Please let me know if I can assist you with anything else.