How to get sécurité sociale

So I from India I hold the French carte d'identité and passeport which I basically got through descent (my mother is a French national) I recently turned 18. Im actually planning on studying medicine and surgery in Italy this year. I will be moving to France soon for a few months before moving to Italy. So basically I want to apply for the European health insurance card coz the health insurance in Italy demands it for the ssn (which is the health insurance kinda thing there) I found that to apply for ehic I need the sécurité sociale but I think its given to the people who stay and work or study in France. I mean like I would be staying in France for atleast 4 months before moving to Italy. So my situation is kinda critical coz I couldn't find anything which could be helpful.