Some buildings need a password to enter the downstairs door. Is this a unified password for the whole building?

You need to enter a password to enter this building. The password only allows you to open the door under the building. But when you enter the home, you must knock at the door. Or directly enter the floor number of the house you want to go to, such as No.203 on the second floor, and then enter 0203. If it is No.7 on 10 floor, then enter 1007.