How do I install MindStream?

The link to the program is listed in the original Store entry:
http://store.neurosky.com/products/mindstream

It brings you to a product description that explains the Github code here:
https://github.com/ericblue/MindStream

So the way this program is distributed, per it's specific license, is as code that you will need to compile yourself. There's information from the Github page itself. Here is what it says:

[Installation]

Currently there is no installer. You can download the source and/or binary distribution:
the primary executable (mindstream.jar) is located in the dist directory. There are helper scripts to execute loading the app (mindstream.sh for Linux/Mac and mindstream.bat for Windows). Both scripts simply execute ( java -Djava.ext.dirs=lib -jar dist/mindstream.jar).