How to download a symbol/footprint using the SnapEDA plugin in PCB123
In the Main Schematic or Layout Editor window, click Insert on the Menu and select Add Part(Symbol) or Add Component(Footprint).
In the Select Part window, click the SnapEDA button to access the SnapEDA plugin.
Once you're in the SnapEDA plugin window, type in the part number you need and press Enter.
Click on the part number you need, then on the upper section of the SnapEDA plugin window, scroll down, and click Download on SnapEDA.
It will then direct you to the part page on your browser where you can download the library.