Install polybar with yay:
yay -S polybar
Copy default config to ~/.config folder:
cp /usr/share/doc/polybar/config ~/.config/polybar/config
Add these lines to ~/.config/bspwm/bspwmrc.
# polybar
# kill previous instance(s)
killall -q polybar
# create a new instance
polybar palenight-bar &TODO: work in progress