Use SD card as storage ReTerminal

Hello,

I have bought a ReTerminal with Raspberry compute module 4 with EMMC and I would like to use the SD slot as storage.
But when I put a SD card inside, nothing happens (32Go Fat32 sd card).

Is it possible to extend the storage with this method or is it just to boot with a 2nd OS ?

Thank you very much in advance

Benji