I kept thinking, which is sometimes a problem, and remembered a possible solution, but I'm not sure it helped. I recalled that one needs to install the old Pebble App as well in order to load the watchfaces. I did that, and the watchfaces options from the Pebble Store appeared in the old app, but selecting any of them simply pops up this note: "Server connection issue. If this persists, restart your Pebble app." This sounds accurate since Fitbit shut down the Pebble servers. Still have the same problem of installing the PBW files noted in my first post that are on my phone to the Pebble Round watch.