Signed-in users can also find this guide, with screenshots, under Help in the app.
An assigned spot belongs to one unit. Only that unit can book it, and staff can see which car should be there.
Open Parking and select the area, for example Resident Garage.
Select the spot on the board.
Under Assigned to, choose the Unit.
Optionally choose a Resident (optional) and a Vehicle (optional). Leave them on Anyone in the unit and Any of the unit's cars if the spot is shared.
Select Save assignment.