This board combo is for use with the Sega Dreamcast to allow you run Dreamshell off of a SD card and allows you play a decent amount of ISO images and emulators but the best thing about it is the ability to RIP GDRom games so you can backup any games you own.
This board install is not too hard if you have some soldering experience and use a thin tipped soldering iron along with flux (I can’t stress the use of flux for this to succeed), and just line up the PCB into the back of the serial port pins and do one pin at a time using a drag method from PCB to Serial Pin.
You do need a Dreamcast that can read CD games (the last revision does not allow this) to boot the Dreamshell software (freeware), the Dreamshell software is on the SD card and the CD acts as a boot disc to load the executable from the SD card so if the Dreamcast can’t read CDs then this won’t work in your console.
The Software is also picky about certain SD cards and sizes, what has been proven to work reliably are 8GB class 10 SD cards but the Dreamshell Beta images are more forgiving in what SD Cards it accepts. If the SD card isn’t recognized it’s likely not the board unless the soldering is questionable, try a different SD card.