By default Native Instruments installs the VST2 plugins to C:\Program Files\Native Instruments\VSTPlugins 64 bit, or at least that's where it installed on my machine. We have a video tutorial on adding VST plugins to BIAB, which although it is a very old video, the steps today are still the same.

If you're using the 32-bit version of BIAB then the folder path should be C:\Program Files\Native Instruments\VSTPlugins 32 bit


I work here