Hi @Will
For starters, I want to mention that the CFSReader is now part of ParaView and available in the nightly binaries ! Just download the last nightly from https://www.paraview.org/download/
more info here: About integration of CFSReader
To fix your error, you need to install Qt5 and set the Qt5_DIR correctly, see the compilation guide here:
https://gitlab.kitware.com/paraview/paraview/-/blob/master/Documentation/dev/build.md#windows
Hth