Thanks, @hermine.potter. I downloaded GnuWin from that link, and it gave me an installer for patch-2.5.9-7-setup.exe. Forgive my noobness, but is this the file I need? I haven't extracted it yet -- not sure if it goes in the msys64 directory or somewhere else. (I did try getting patch through msys64, but got the same failure messages.) I appreciate your help!
EDIT: I extracted GnuWin and Python and attempted to patch msys64\src, but after the cmd prompt opens, and after patch.exe opens, all I get is a blinking cursor in the patch.exe dialog
I'll keep trying the pacman method. Unless I've overlooked something? Thanks!
EDIT 2: That didn't work, and I'm still getting the same failure message when I try to get patch via pacman
Any other ideas? Thanks!
EDIT 3: All right, I found patch-2.5.9-7-bin.zip, but I'm not sure where I should extract its contents? As you can tell, I have no idea what's going on! Thanks again for any help anyone's able to provide!!!