To use these overlays, you will need to place the CRT folder in your overlay folder on your Pi:

/opt/retropie/configs/all/retroarch/overlay

You will then be able to access them from the Quick Menu as seen below:

1080p Settings	Value
Aspect Ratio	Custom
Custom Aspect Ratio X Pos	480
Custom Aspect Ratio Y Pos	180
Custom Aspect Ratio Width	960
Custom Aspect Ratio Height	720
Integer Scale	Off

Most of these overlays need a curved CRT shader to avoid cropping too much in the image corners. On my RetroPie setup, I use the CRT-Pi Curved shader with most settings at default, and this change:

Shader Variable	Value
Screen Curvature Vertical	0.25