Import Symbols
Using the *.lib file:
Extract the content of the downloaded *.zip file.
In KiCad, go to Tools > Edit Schematic Symbols.
Click on Preferences > Manage Symbol Libraries.
On the Global Libraries tab, click on Browse Libraries (the small folder icon below)
Select the *.lib file. Then click Open.
The library will appear, click OK.
Type on the filter search field, and navigate to the symbol you imported. Double-click over it to open the file.
Import Footprints
Using the *.kicad_mod file:
Extract the content of the downloaded *.zip file.
In KiCad, go to Tools > Edit PCB Footprints.
Click on Preferences > Manage Footprint Libraries.
On the Global Libraries tab, click on Browse Libraries (the small folder icon below)
Navigate to the Folder where the *.kicad_mod file is located. Then click Open, and the library will appear.
In the table, make sure that the Plugin Type is set to KiCad. Then click OK.
NOTE: If the path doesn't have the same name. you can rename it as the part.
Type on the filter search field, and navigate to the footprint you imported. Double-click over it to open the file.
Using the *.mod file:
Follow the same steps above from step 1 to step 4.
In the table, make sure that the Plugin Type is set to Legacy. Then click OK.
Toggle the search tree on, and navigate to the footprint you imported. Double-click over it to open the file.