The underlying Linux operating system that RetroPie runs on top of is intrinsically multiuser.
You only need a free TeleTYpe program (I recomment putty for Windows) to gain access from your laptop in the same way as WinSCP does to move files.
Username pi - Password raspberry
The pi user does NOT have administrator rights, but the 'run as super user' keyword "sudo" can be used in front of any commands that needs them (no admin password required).
Make the terminal window as big as you need and use the nano editor to change configurations.
bye.