I am on a Windows 10 64bit system using Audacity 2.0.6 after reverting from 2.1.2 over this issue. The MJUC jr plug is placed in the plug ins folder, shows up as an option when i run Audacity but does not show up in effects. There is no add effects function anywhere either… unless i haven’t figured it out.

Audacity 2.1.2 has a plug-in manager, accessed via “Add / Remove Plug-ins” at the top of the Generate, Effect and Analyze menus.
Details are in the manual here: http://manual.audacityteam.org/man/manage_effects_generators_and_analyzers.html

ah. got it now. thank you.