The organism called International Students and Scholars Office - ISSO for short (studenthousing@grenoble-univ.fr) is devoted to help students, in particular for the accommodation. Therefore, you should contact them as soon as possible. It may be the best option. You should mention that you have been accepted to our M2R in fundamental Mathematics and that I have told you to contact them. Do not hesitate to put me in copy of your message (andrea.pulita@univ-grenoble-alpes.fr).
Please also check these pages :
https://international.univ-grenoble-alpes.fr/fr/etudiant/logement/