The default user is admin and the password is admin.
If you do not have access, we will have to generate a temporary key, to recover the forgotten password.
For this we need the MAC address of the device to be sent to us.
In cameras you need to use DeviceConfigTool (in the product pages' download section you will find the latest version) to visualize the MAC address that the tool needs:

DeviceConfigTool:
https://athena-visiotech.s3-eu-west-1.amazonaws.com/7l9nGW8B3rdHzDKKRPq6/Device%20Config%20Tool_1.0.0.33_2017_05_12_282.exe
So you can see the MAC address on the recorder:

This process is done the same way for all these models
- NV-KIT41-4CAM-5M
- NV-KIT41-4CAM-8M
- NV-KIT81-4CAM-8M
- NV-KIT61-4C2M-BAT
- NV-IPDM940HA-5
- NV-IPCV020H-5
- NV-IPCV020H-8
INTERNAL