A bit late but since you get an email you may read this anyway.
If you install BOLTSFC by the addon manager wait some time ... may be 5 minutes. It will not tell you it is successful installed, but it will copy it anyway. Open a Python Console in FreeCAD and put in
If you get no error message BOLTS is installed.
Afterwards go to your FreeCAD Mod directory. There should be a file called "start_bolts.FCMacro inside the BOLTSFC directory. Move this file into your macro folder. Run this macro to start BOLTS.
for reference: https://github.com/FreeCAD/FreeCAD-addons/issues/102