I use my laptop most of the time because i'm away of my gaming desktop during the week. Honestly I don't know the answer, not much a tech guy, sorry... Anyway an external ssd is not an option right now because of the costs...
I still find bit strange so many space just for a default map and no modules but I guess I'll have to accept the fact that for now no DCS for me.
Many thanks hornblower and Rudel for your kind assistance.