Welcome!
Outpost was written for 16-Bit computers (specifically Windows 3.1 which never came in a 32bit version). 32Bit flavors of Windows were able to run 16bit code using an emulation core (NTVDM I believe) which was dropped in 64Bit versions.
If you have any issues running the package we put together head on over there and post away, I'll gladly answer any questions you may have.