type diskpart into windows search and press enter
Type list disk in the command prompt. Find your drive, looking at drive size is usually a key indicator of which drive is which.
Type select disk # replace the # with your disk number, for example: select disk 1
Warning: the next part will delete everything on the drive, so be sure you selected the right disk:
Then type clean
Now type convert mbr
Now you can close the command prompt and open Disk Management.
Right click the Unallocated space of your drive, select New Simple Volume
Format it to FAT32 with 32kb cluster/allocation unit size
If the drive is larger than 32gb, you will need to just assign it a letter but instead of formatting, select 'Do not format this volume'.
Some windows may pop up. Just say cancel when it asks to format again and then exit out of the other window.
Use a third party program like Wii Backup Manager or GUIFormat to convert it to FAT32.
https://wii.guide/wiibackupmanager or http://ridgecrop.co.uk/index.htm?guiformat.htm
Format it to FAT32 with 32kb (32768) cluster / allocation unit size.