How to enable usage of the WaveLab Pro 12 free trial?

As the instructions told me, I enabled the latest Steinberg Download Assistant. I was able to log in with my account. I tried to install the WaveLab Pro 12.0.51 Full and Update Installer but the download does not complete. A message says that I should Install again. How can this be corrected?

Updates & downloads for WaveLab 12 | Steinberg

You can download and Install WL from here, activate it through the Steinberg Activation Manager instead of Download Assistant.

Steinberg Activation Manager | Steinberg