Homepage › Forums › RetroPie Project › Everything else related to the RetroPie Project › USB doesn't work in 3.0 (beta3) › Reply To: USB doesn't work in 3.0 (beta3)
Create a folder called retropie
on the usb drive first and it will place the ROM folder in there.
https://github.com/retropie/RetroPie-Setup/wiki/How-to-get-ROMs-on-the-SD-card