On my computer, those messages appear even though some of those libraries are installed and in use.
Each of those libraries are packed in a .zip or .jar file,
or in some cases a .mc3lib file which is actually the same thing: a compressed zipfile.
You may download each or all of those update files from the MCC webpage:https://www.microchip.com/mplab/mplab-code-configurator
scroll down to Downloads tab.
There is only one Plugin, which you probably already have installed. The current version is 3.85.1
Then there are a number of library packages that are used by the MCC plugins,
the library packages are Not plugins by themself.
You may download those library files to a directory of your choice.
Then in MPLAB X IDE, in menu: 'Tools', select: 'Options' (not Plugins),
this will open a big panel with various icons along the top.
Click 'Plugins' in the options panel, it should show a single tab 'MPLAB Code Configurator 3.x'
click button 'Install Library', this will open a file browser window: 'Choose library file',
now you will need to remember what you did before, and locate the directory where downloaded files are located,
select the downloaded library file, .zip or .jar or whatever, select the file and click 'Open',
what now actually happen, is that the file is copied to a directory where the MCC plugin know where to find it.
There is also a button 'Open Library Folder' , so you can see what is already there.
You may have any number of versions of each library available in the library folder.
When MCC is running, there is 'Versions [MCC]' panel in the lower left corner of MPLAB window.
There you may see what versions of each library is available, and select which version to use.
Currently selected library version is indicated by a 'green checkmark',
if you want a different version, RightClick on the version line to select.
On the MCC webpage, there is a Release Notes document for each library.
It have documentation of the steps described above, together with list or tables for what families of devices are expected to work. There is little or no description of how the code work or is used in the release notes.
For some libraries, there are a help browser indicated by a blue (?) questionmark icon.
Documentation is still pretty poor for many libraries in MCC.