Using an Mac-used External Drive on a Windows

I'm a teacher and I (on behalf of my students) need your help. I have a bunch of (extermely important) files and lesson plans I need to acces, which are on a Seagate external back up drive. I used this external drive on a Mac. Now that my Mac has been stolen, ( yes - it's sad, I know; I'm coping) , I need to access my saved files on this drive, but using a PC this time (because it's all I have at the moment - again, I'm coping).

So, I plug it in - all cords and systems go - but the drive doesn't show up in the Computers folder. Although the PC actually recognized something was indeed plugged in (the bottom right hand pop up said it did), it doesn't show up in the Computers folder.

What do I do to see my files on a PC? Thank you to all who help!