I followed the steps Paul Girardin wrote above and installation and activation went without any problems.
I was able to install as administrator, and activate offline by sending an activation request file to the emailadress in the program. Microsoft sent me an email back within two hours and I uploaded the file into the software. Activation successful.
Unzip to a new folder (\MSTech) in my archives folder.
Install, write the license key, and tried the Writer
Everything OK, evrything works!
… now my MSDefender anti virus warning me, and erases the EXE files!
And 2 weeks later, the problem not solved.