Download the source from github, which can be achieved via the following in a terminal, which will create an isofinder directory in your current directory:

git clone https://github.com/sean-dougherty/isofinder.git

Move to the isofinder/version1 directory:

cd isofinder/version1

Execute the Makefile:

make

You should now have an isofinder binary in your current directory, which can be invoked with no arguments for usage information:

./isofinder