undefined symbol: fftw_taint (/lib/x86_64-linux-gnu/libfftw3_mpi.so.3)
undefined symbol: fftw_join_taint (/lib/x86_64-linux-gnu/libfftw3_mpi.so.3)
Several people have stumbled upon this issue, and it looks like it is always related to building OpenFOAM itself from source, while having FFTW already installed on your system.
Removing FFTW from the ThirdParty directory of the OpenFOAM source code, and running Allwmake in OpenFOAM (not the adapter) should help. This should also be very fast, as it will only relink, not rebuild.
I am adding this to the documentation of the adapter: Get the OpenFOAM adapter | preCICE - The Coupling Library