You can add the libs manually to the lib table by use of the library manager (assuming the libraries are installed) See Library management in KiCad version 5
You can also download the lib table from github and copy that one to your config directory Where are the configuration files (settings, library tables)? If you use this option then make sure the path variables point to the correct directory. (Benefit you get the library descriptions we add to the official lib. Downside you might need to handle path variables)
If the library files are not installed then download the lib files from github. Details in the library management FAQ article posted above (section “Updating the official library” and below)