Using 8TB My Book as a storage device for my NVR videos

How can I use my external as a storage until I can watch the video
I do paranormal investigations and I need to watch them but have limited time right now.
I bought a WD 3TB internal and put in the NVR but when I plug the 8 up to it to back up with it does not recognize it… I’m at a road block any help will greatly be appreciated

thanks

I think you should check the instructions for your NVR.

It says nothing about a external Hard drive… it’s a two page instructions sheet… it’s a made in China deal
But I bought and installed the 3 tb hard drive that’s in there and has the videos on it… is there any way I can get those to my 8TB