In the interface, any Hik IP cam (and many ONVIF IP cams too) will auto detect and get added to a list (refreshed every few seconds). Then you choose all the cams you want to import.
In the case of new Hik cams, you enter the new passwords you want to setup for them in the 1st step. In the case of cams already setup or other manufacture cams, you manually enter the existing credentials and then choose your new passwords.
The only time this gets frustrating, is when you have a cam that won't auto populate. Very rare but it does happen.

[edit]: Think of it like this. The NVR is constantly running a FING search on its POE ports. When it finds a new device it recognizes as an IP cam, it gets added to the list with whatever info it knows about it (again, think FING). You can then choose to, or not to, import that device to the NVR setup.