If you have an older versions of the software prior to the 3.0.0 release, then you need to head out to the official website to download the latest package. According to the system requirements, you can run the software on NT, 2000, XP and later. This means Windows 10 is supported and the Free Pascal can be used normally.
For every time you run the software, right click it and choose Run as Administrator and then run the program you have. It's mandatory to run apps as Administrator especially when they're installed on the system partition.