Bought a used portable drive from someone, is it legit?! please help!

I bought from Mercari and its supposed to be 8tb drive… when I plug it into my PC, it says it’s all set up, but in my settings under devices, its saying drive unavailable… so I thought maybe I had to download drivers for it?? I didnt have to on my brand new one I bought soo I dont know… also on the WD website I see you can run tests on the hard drive to make sure it’s in good health… upon running the dashboard… up in the right hand corner under devices, it gives me the option of 2 diff devices… first one is wd blue pc (disc 0) and 2nd device is my book (disc 1) … can anyone tell me why this is or what it means?? when I choose the wd blue pc disc0, it says it has 1tb of space… and then if I choose the my book disc1 it says i have 8tb of free space. The person sent me the orignal box as well… however the serial number on the box is not the same serial number as the one on the actual hard drive… when i put botrh serial numbers into the warranty status on the WD website… it does say that both warranties are expired, which is fine, i figured as much… and both say 8tb… i just want to make sure this hard drive is legit and I can trust it to transfer my files on to… im just really confused about the disc0 and disc1 i guess… can someone help me please! i have 3 days before the sale is final thru mercari, so if theres any issues I need to get it figured out now so I can request a refund and send this drive back to the seller. thank you in advance!!

Ughhhh okay. It was such a good deal tho, didn’t want to pass it up… however, the good price should’ve been a sign to not trust it from the jump. Thank you!!