You all might be using different types of disk subsystem in Windows OS. If you have had a tough time figuring out going to each folder and understand what's the space left like below, here's an easy method.
If you open D drive, you'll see many folders (looks like shortcuts).
Since you're a DBA, you can use this command to find out the space and free space left in each folder.
Yes, sp_fixedluns came in very handy for me. I'd be glad if it helps you.
-KKB