There's a newer version of SC4Mapper, called SC4Mapper 2013, which is up on the LEX
here. It was designed prior to Windows 10 (Windows 8 was the newest version at the time), but I have it running without issue on my Windows 10 machine, right out of the box.
I'd also recommend running a 4GB Patch over the SC4Mapper 2013 executable--if you've downloaded the latest NAM (NAM 37 just came out yesterday!), there's a copy of the NTCore 4GB Patch right in the directory. Otherwise, you can pick it up
here. When you open it up, just point it toward SC4 Mapper 2013 (default install directory is C:\Program Files (x86)\SC4Mapper 2013). That handy little patch will flip the "Large Access Aware" flag to "on", which allows the program to access more RAM (4GB instead of 2GB), improving performance, and letting you load larger maps.
Hope that helps!
-Alex