The most likely reason for the installation failure of a 64-bit software is that the operating system is incompatible, specifically if the system is running a 32-bit version of the OS. A 64-bit program requires a 64-bit operating system to run, and if the user's OS is a 32-bit version, the software will fail to install. Other reasons, like needing administrator privileges or updating .NET, are valid but less likely since the error message would be different. Reference: Microsoft Support: 32-bit and 64-bit Windows: Frequently Asked Questions CompTIA A+ 220-1102 Study Guide (CompTIA) (ProfMesser)