Hello, without the entire development plan, I cannot give a "binding" answer. I just took a quick look at the profile, I assume the construction site is located in S-H? Garages of this size are not exempt from approval (height and floor area), but you are welcome to send me the development plan via PM or also here or provide the designation. Then I will gladly take a quick look :-)
Theoretically, I would tend to think that secondary structures as a whole should not exceed 15 sqm of floor area. A garage usually does not belong to secondary structures. Garages, however, are not secondary structures - these are covered by §12 of the Land Use Ordinance. A garden house/heating room - if it is structurally separated from the rest - could be placed there. Regarding the height and size of the garage's floor area, I would really need to see the development plan - especially since you are not planning any setback area. At a height of 4.70m, one could possibly be required. At the very least, the neighbor's consent should be included in the building application - this always pleases the building authority ;-)
Best regards