Our DVR can't support the external hard drive, you need to buy a professional surveillance internal hard drive to install.
It is not recommended that you purchase a PC hard drive.
(Like 3.5 inch Seagate Skyhawk, Sumsung or Western Digital (purple))
Note: The max hard drive size supported by our DVR system is 6TB.
We suggest you buy Seagate 1TB or 2TB hard drive.
You can follow up the below video to install and format the hard drive:
Some related problems for your reference:
If this can't help you, please feel free to contact us.