Not sure, as I don’t have that particular model, but does the NVR come with a hard drive? If so it may have been shipped with the cable disconnected. This was made clear in my installation instructions although mine WAS connected.
Power it down and open it up to check. Connect it if not already connected. Then after you power it back up be sure to check for any firmware updates.
If no hard drive then you will need to install one via USB. You can either buy an actual external HD or just plug in a high capacity USB stick. If you only have one USB port then unfortunately and quite annoyingly you will need to buy a USB port extender/expander otherwise you won’t be able to use a mouse to access the menu while the drive is connected. Kind of self defeating if you ask me.
BTW, anyone getting ready to tell me I am wrong, go back to my first sentence sentence where I said in the beginning I don’t have this model. As such this is a generic, but still useful reply.