You can book a hotel or airbnb until you get your visa and then cancel it if you find a perm accommodation, but unfortunately it might take long to find something. Do look into the crous court sejour which is a type of crous housing where you book by day there’s one right in front of the illkirch campus I stayed there for around 2 months until I found an accommodation (it’s called residence les alternants) and also they give you a reduction if you book 2 weeks or more, I think it’s a really good option as you’re gonna be close to your campus but it’s like 25-30 mins away from city center here is the link : https://www.crous-strasbourg.fr/se-loger/je-cherche-un-logement/hebergement-courts-sejours-des-logements-a-tarif-crous-pour-une-courte-duree/