SYMPTOM:
"MiSSING: Windows Installer 4.5 or higher." which halts the installation process is in the screenshot as shown below.

Strategy Office Requirements:
MISSING: Windows Installer 4.5 or higher.
CAUSE:
Strategy Office requires Microsoft Installer 4.5 or higher to be installed prior to the installation. The Windows Installer is a software component used for the installation, maintenance, and removal of software on Windows systems. Microsoft encourages third parties to use Windows Installer as the basis for installation frameworks, so that they synchronize correctly with other installers and keep the internal database of installed products consistent.
ACTION:
In the case motioned above, download Windows Installer Version 4.5 with the link: http://support.microsoft.com/kb/942288
NOTE:
The latest version of the Windows Installer is 5.0. However, it is only available for Windows 7 and Windows Server 2008. So the version 4.5 should be installed, when installing Strategy Version 9.21 on Windows Server 2003 64-bit platform.
WARNING:
The third-party product(s) discussed in this technical note is manufactured by vendors independent of Strategy. Strategy makes no warranty, express, implied or otherwise, regarding this product, including its performance or reliability.