Yeah what Floob says. It sounds like you compiled RetroPie yourself. If you use the SD card image it’s much more noobie friendly. Also, since it’s an image of the whole OS, there’s lot’s of little tweaks included that you don’t get when you install RetroPie on top of Rasbian. Like a modest overclock that really is needed to run the included emulators.
Bonus – it won’t take nearly as long as building RetroPie from sources 🙂