To answer the original query – – the direct download link no longer exists publicly. However, by following this guide, you can:

Several community members have uploaded ISO images for Windows Embedded CE 5.0. HPCFactor: This community site sometimes hosts the 120-day Evaluation Edition HPC:Factor 3. Requirements for a Working Setup

To actually use Platform Builder once downloaded, you typically need:

For those specifically needing the Platform Builder environment for legacy maintenance: Windows CE 5.0: Standard Software Development Kit (SDK)