Placement of house, terrace, carport & co. in the building window

You have listed two different plots of land. Can you provide an original location plan with streets, paths, etc.? Please use the building envelope from the development plan or upload a copy of the development plan of the respective plot.

The first attachment is the original plot before the reduction to 2,600 m². To the east in a north-south direction is the road, to the north is a pedestrian path. Orange is the building envelope with a 3m setback line, to the left in green is the garden outside the building envelope. The probable layout is visible in the second attachment, the boundaries to the west, north, and east remain the same, the southern boundary shifts north to reduce the size of the plot. The survey has not yet been carried out, so I cannot provide exact measurements yet.

Garages, carports, and parking spaces are only permitted within the buildable areas of the property"

.., where however the boundary development should be included

I think @ypg means the distance to the street, commonly it is 5m here. (This is meant to ensure that you can fully drive out of the garage without entering public traffic areas)

Exactly. However, as you also said, a rotated garage does not have this problem, so these 5 meters might not have to be observed at all.

Does the possibility to place a garage on the property boundary apply only to the neighboring property or also to the street or sidewalk as shown in the above illustration?

You have to tell us that: zoning plan etc. is available to you, not to us.
Since no property dimensions are given in the original thread, here is just a sketch. If the clearance to the street must be 5 meters, then simply nice bushes go in front of the garage or the parking space for the rider who rents the shed.

.., where the boundary development should be included

... provided that the building envelope does not also maintain a 3 m distance from the property boundary, which seems to be the case here. ;) Or does the dashed line not represent its boundaries?

Yes, the three meters have already been deducted from the building envelope.

Plans where the numbers cannot be read are pointless. o_O