If you are looking for an official Microsoft download page for "Windows Installer 5.0 for Windows 10 64-bit," you will not find one. Instead, use these official resources:

If you are seeing errors related to the Windows Installer on your 64-bit Windows 10 system, you can try resetting the service or ensuring your system is fully updated. Essential Information for Windows Installer 5.0

Windows Installer (MSI) is the built-in installation and configuration service utilized by the Windows operating system to deploy applications. Version 5.0 was introduced alongside Windows 7 and Windows Server 2008 R2.

Windows Installer (MSI Executable) is the Windows component responsible for installing software using .msi packages. Version 5.0 was first introduced with and Windows Server 2008 R2 .

Microsoft historically provided redistributable installer packages for previous versions:

Right-click the and choose Command Prompt (Admin) or Windows Terminal (Admin) .

Secures services, accounts, folders, and custom registry keys.

A previous, incomplete installation might be locking the service, preventing new deployment tasks.

On Windows 10 64-bit systems, the installer natively coordinates both 32-bit (x86) and 64-bit (x64) installation directory structures, registry paths, and system dependencies smoothly. How to Check Your Current Windows Installer Version