OK so flashing the Recalbox on a 16GB SD card works fine, then you can format the third partition (even in Windows) as FAT32 in Disk Management, like so:
Upon booting up, Recalbox will detect that partition and set it up with a set of standard folders:
The roms folder is the one you care about, since that’s where you’ll put the games.
Directory of F:\roms
megadrive
pc98
fba
oricatmos
msxturbor
daphne
cavestory
msx2
gx4000
atari2600
sg1000
pcengine
msx1
tic80
satellaview
zxspectrum
scummvm
pcenginecd
mame
gb
lynx
samcoupe
atari7800
supergrafx
snes
o2em
zx81
gbc
fba_libretro
vectrex
virtualboy
nes
gw
x1
ngpc
intellivision
sufami
mastersystem
imageviewer
x68000
wswanc
atarist
c64
lutro
ngp
thomson
amstradcpc
atari800
pokemini
wswan
atari5200
channelf
prboom
fds
neogeo
sega32x
apple2gs
gba
palm
segacd
gamegear
pc88
multivision
neogeocd
psx
dos
spectravideo
colecovision
moonlight
uzebox
It’s sort of questionable how many of these you want to be populated on a Pi Zero, which isn’t going to be able to emulate the fancier stuff anyway.
The ones with default “free” games, which you probably want to remove are:
- amstradcpc
- gba
- mastersystem
- nes
- pcengine
- prboom
- snes
- thomson
A system folder with no ROMs won’t show up in the UI, so this is a way to get the odder ones to disappear.