Where should VST2 plugins be located?

Thank you for the info, Ulf! It is working for my VST2’s, however, Kontakt 5 is not appearing in Dorico. Whether I use the original GUID or a fabricated one, or try listing it as either Kontakt 5 or Kontakt 5 16 out–it is absent from the playback options. What do you recommend for a solution? Thanks!