If you have subscribed to the French Student Health Insurance (Sécurité Sociale Etudiante), you must first pay your fees of medical care (hospital, doctor, drugs, ...) and then ask to be refunded by the "Sécurité Sociale".
The refund of "Sécurité Sociale" is done in a few weeks. According to the spending, the refund rate varies, but is usually 65% of the amount.
The "mutuelle" is an optional additional health insurance. It allows you to receive the remaining 35% and pays in your place ("tiers payant ") the amount of some spendings such as pharmacy or radiology. It is therefore strongly advised to subscribe to a "mutuelle" when registering at INP-ENSIACET.
Two "Sécurité Sociale" centres
If you subscribe to LMDE or Vittavi and if you open an bank account in their partner bank, the latter can be warrant for your accommodation.