NO story told , first time used, this??? just bought it?
is it new or used,? IDK any of that, and data matters.
Ill assUme it is new with no precious data....
no PC stated, , w8.1 why not upgrade for free to w10?

smart disk or any external HDD, or SSD, all need to be formatted
first. you did only the last step. (first)
#1 plug in the USB cable to a working USB port.
2: go to CP control panel then admin tools then computer management and last disk management or.
2b: in the run box type diskmgmt.msc 3: now diskmanagment is OPEN.
4: the drive shows up as a DISK NUMBER. only
5: right click your DISK seen in the list, do not pick Disk 0
6: make sure the DISK U picked size matches your external disk size.~~
7: right click the DISK1 or what it is and pick new simple volume
8: right click disk1 and format it. to fat 32 or NTFS.
9: assign a drive letter to the new drive, (from now on the drive external shows up in windows explorer as drive letter same.

that is it, same story on new empty USB thumb drive !