These are the steps to add parts to the library into KiCAD v5.1.9.
Note: Make sure that your KiCAD is connected in your Tools tab.
Open SnapEDA Desktop App
Search and click the part that you want to download
Then click Add to Library on KiCAD
Note: This might take a few seconds but please don't click the button multiple times. Wait until the notification appears
After a few seconds, KiCAD PCB New will automatically open
The reason why we are opening the PCBNew footprint layout instead of the schematic is that KiCAD doesn't yet support APIs with the schematic layout.
Add footprints on KiCAD and see that the part is now under SnapEDA Library
If you want to open or place the symbol on the Escheema, simply search the part downloaded on the Choose Symbol window or Symbol Editor window.