Moved to ePO for better support.
it's on page 9 of the install guide:
"Supported server‑class operating systems
The software requires one of these supported 64‑bit server‑class operating systems.
Supported Operating System 64‑bit
Windows Server 2008 (with Service Pack 2 or higher)
Windows Server 2012"
Basically ePO 5.x supports 64-bit OS only.