All you have to do is to double-click the application's executable. I've just installed it on a 64-bit Windows 10 PC, and it runs just fine. However, the version you download from Software Informer is just a trial one and if the 14 days that you get for free have expired, Cassette To MP3 Plus will no longer run.
Unfortunately, it seems that the application has been discontinued as its official website is no longer available. This means that once the trial is over, you won't be able to purchase the tool, so you can't use it anymore.
In case you need an alternative solution, Audacity can help you transfer songs from cassette tapes to your computer.