The software download itself is free, but using it requires a valid license. You can download the installer with any SAP S-User ID that has access rights, but activation requires a purchased license or a time-limited trial key.
Even for client-only, download the full WIN_X86_64 ZIP file. The Designer setup is inside. sap data services designer download
If you cannot access the official SAP Software Download Center, consider these options: The software download itself is free, but using