The "Plug-Ins" folder is the standard place to "install" Acrobat plug-ins. After installing a plug-in you need to Quit and restart Acrobat Exchange or Reader.
To install Acrobat Plug-Ins
Place the plug-in inside the "Plug-Ins" folder within the "Adobe Acrobat" folder.
To un-install Acrobat Plug-Ins: Drag the particular Acrobat plug-in you want to un-install from the "Plug-Ins" folder to the "Optional Plug-Ins" folder.
Note: For Acrobat Exchange 2.0, the name of the parent folder was "Adobe Acrobat 2.0." Not all plug-ins are designed to work with Acrobat Reader 2.1 and Acrobat Reader 2.0 does not support plug-ins at all.