Hikvision does not offer a cloud service, the cloud you refer to is that a cloud service you pay for?
Usually, these 3rd-party cloud services will only be for storing recordings and you won't be able to access the live view of the cameras or any settings from within the cloud software.
if you are accessing the cameras locally inside your router's network then the cameras and NVR would be on the same IP range (192.168.1.xxx) and you can log in into the NVR or any camera by simply typing its IP address into a PC browser on the same network. If you were to try and log in with the same addresses while connected to another router or while using 4G you will NOT be able to log in.
To remote access, you would need to port forward, which is when you open a specific port on your router for remote access. An example would be if you port forwarded port 80 on your router you would then need to add this port number to your IP address to gain access to the local network. (e.g. 192.168.1.100:80) If you don't port forward then the system is only accessible from devices also on the same local network. (e.g. 192.168.1.xxx)