Do not use third-party websites. Go directly to the official Siemens support portal:

Using the HMI programming resources to create custom user screens.

Before downloading, it is crucial to understand what the Toolbox contains, as you might not need to install every component. The Toolbox is a comprehensive software package designed to facilitate the commissioning and maintenance of the SINUMERIK 828D CNC. The exact contents can vary slightly depending on the version, but it generally includes:

Create a free account. Access to specific engineering downloads requires an "Export-Controlled Software" registration, which takes 24–48 hours for Siemens to manually approve.