Well, download it from http://www.fuzzylite.com/downloads . You can either purchase a license of QtFuzzyLite 5, or use the free community version QtFuzzyLite 4.
FuzzyLite
The FuzzyLite Libraries for Fuzzy Logic Control
Fuzzy Logic Control was never this easy, simple, intuitive, beautiful, exciting,
and more importantly, completely based on free and open source technologies.