Recently, some people have been experiencing an issue where they get a blank white screen when they download Qlik Sense Desktop. This post and this post go through some good things you can do to try and resolve the issue, and you may also want to try downloading the latest service release version of Qlik Sense Desktop, and running the repair option. Another thing to check, particularly for people who are installing Qlik Sense for the first time, is the machine's .NET framework version.
If we take a look at the Qlik Sense Desktop system requirements, you can see that it requires version 4.5.2 (higher versions should also be ok). There are several methods you can use to check your .NET framework version, which are outlined on this page as well as this one. The method I have found easiest to use is to simply enter this command into your command prompt:
wmic /namespace:\\root\cimv2 path win32_product where "name like '%%.NET%%'" get version
To do this, go to your 'Start' menu, and search for 'Command Prompt'. Right click on that, and choose 'Run as Administrator'. Once the command prompt is open, simply copy the above line, and paste it into your command prompt (fyi, you'll have to use right click then select 'Paste' - CTRL+V won't work in command prompt). Then hit enter. Once the command has finished running - be patient, it may take a few minutes - it should display the .NET framework version you are running. Mine shows I am running version 4.6.