You can install the recalboxOS on a fat32 formatted sd card.
Use a card formater software from https://www.sdcard.org/downloads/formatter_4/ on Windows and MacOSX, or gparted on linux.
Start the SDCard formatter program and format the whole card in FAT32.
Download recalboxOS.zip from the last recalboxOS release at https://github.com/digitalLumberjack/recalbox-os/releases
Now unzip the recalboxOS.zip file directly at the root of your SD card. Delete the zip file in case you copied it to the SD card!
Put the card in your Raspberry Pi, plug in the hdmi and the power supply.
The installation starts, you'll have a recalbox in 5 minutes !
At the end of the install, the Emulationstation screen will show up, and you will have the pleasure to listen to the awesome Zelda theme!
1) Download Win32DiskImager from https://sourceforge.net/projects/win32diskimager/files/latest/download
2) Download an image in .img format once available
3) unzip Win32DiskImager-0.9.5-binary.zip and run Win32DiskImager.exe
4) Extract recalbox.img.gz (gz is like zip, ie it's a compressed file)
Warning: Some browsers like Opera, Chrome and Safari take the liberty to unzip the file automatically and badly rename the contents. If the file is more than 1GB, it is already unzipped.
5) Insert a USB flash drive or a SD card on your computer
6) Select the image and the drive in Win32DiskImager.exe like on the following screenshot and click on Write
7) Once finished, go on your USB flash drive/SD card and check that it looks like this: