You can download compiled binaries here.
Make sure to edit path to wow folder in config file before use.
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First grab the code using git:
git clone https://github.com/WoW-Tools/CASCExplorer.git
cd CASCExplorer
git submodule update --init --recursive
Use Visual Studio 2017 15.7.0 or higher to build it once you have all dependencies.