Where are you trying to download the Qlik Sense desktop from the Qlik website? Since June 2020 it is no longer possible to download it because the product is no longer free. You can read the following article (link)
To use Qlik Sense Desktop, you must be a Qlik Sense Enterprise On-premise or Qlik Sense SaaS customer in order to authenticate to Qlik Sense Desktop and use the qvf files. In the article I put before there is a download link for the latest version of the Desktop (Qlik Desktop) or you can ask your Qlik partner to pass you the installer.
In the case that you are a Qlik Sense SaaS customer you can enter profile settings -> Tools, you will find a link to download the latest version of Qlik Sense desktop.
This document tells you how to authenticate Qlik Sense Desktop