When you did the trial download did you run the setup from the web or did you save it to your machine and install it from there?
If you saved it to your machine then you should be able to just browse to the "SI5-trial.msi" when prompted to finish the setup.
If you ran it from the web then email
http://www.d-tools.com/support/submit-an-issue.html and we will send you a direct link to download the files again. Then you can save the download to your machine and run it from there.