Assuming you have brought a brand new car, the under board volume has been reduced, such that it will not accommodate a normal spare wheel. I’m not familiar with the space saver wheel dimensions, but I doubt it will accept that either, hence the supply of tyre repair gunge!
I was initially concerned myself when I brought my Mk3 Ex, but simmered down, when I realised how old I was (80+) and would probably be incapable of changed a wheel, by the roadside myself, not to mention the safety issues involved with the general standard of driving nowadays 🤠