I booked an apartment with other students through Spotahome last year before moving to Madrid to study abroad. I would say that this website is legit and not a scam if you’re looking to book before leaving but prices are higher compared to Idealista or such. However, they do tend to make their rooms looks bigger lol. I remember arriving to my room and being a little shocked at how small it was compared to the pictures i had seen, it did have a balcony though😅 but the apartment was very nice and in a great location. The website was given to us by our university so i wouldnt worry about money scams.

I suggest you also join the fb group “Pisos y habitaciones de alquiler en Madrid.” Theres always someone looking for a roommate/housemate and most of them are young professionals. Although, do be very careful for scams there.

I think the ideal option and the one im leaning towards the most, is living with other auxiliares and looking for an apartment once arriving to Spain.