Shotcut 17.08 portable does not run

Hello, I try to run shotcut 17.08 portable on my business laptop, where I am not able to install software. So I downloaded the 64bit version of 17.08. portable and used 7-zip to extract the files into one folder on my USB-stick. While unzipping I directly get the first error messages as some file seem to be double on the donwloaded zip-file and 7-zip asks me, which version I want to save. I chose to use the newer version of the several files, where is meassage comes up. When I then try to start shotcut I get the error message "This application failed to start because it could not find or load the Qt platform plgin “windows” in “”. What am I doing wrong?

Thanks for your help in advance!