Define a "default" footprint, in addition to footprint filters. This is a new feature in KiCad 6 which I was previously unaware of. It allows enables footprint preview in the symbol selection dialogue.
I am a new Kicad 8 user on a Mac and it took me a while to figure out how to install it.
There is no Preferences->Preferences on a Mac for step 2 so I could not figure out how to do steps 2-7.
I did successfully install the library using the main panel with the "Plugin and Content Manager" at the bottom of the screen. Macs automatically unzip zip files when downloading so I needed to re-zip and/or re-download the file but it all seems to be working after using the zip.
The relevant datasheets for parts W65C134S8Q and W65C265S8Q do not list the pitch of the part. This doesn't stop me from creating the symbol, but it means I've had to leave the Footprint filter vague (e.g. LQFP-80* instead of LQGP-80_<size>_<pitch>). If anyone knows the correct size/pitch of these parts, I'd be much obliged if you can let me know.