Try the AOLSERVER.INSTALL file. If you follow all those steps, it should work. It explains how to build and install the the pieces of openfts.
After that you need to install the openfts-driver in your openacs install.
There are two sql files you need to run on your database to build the required things for openfts to work.
So, again, check the AOLSERVER.INSTALL included in OpenFTS. It helped me get everything working.