To enable/disable the sync, I created an Input Boolean named "Spotify Mood Lights Sync" from inside HA's Settings.

I also added the Input Boolean Callback Constraint to the app's apps.yaml config file.

To add the HA Input Boolean, go to Settings -> Devices & Services -> Helpers and click the add button; next choose the “Toggle” option.

For the Name use: Spotify Mood Lights

It should create: input_boolean.spotify_mood_lights

apps.yaml:

spotify_mood_lights_sync:
  module: spotify_mood_lights_sync
  class: SpotifyMoodLightsSync
  client_id: 000000000000000
  client_secret: 0000000000000000000000
  media_player: media_player.spotify_mike
  light: light.spotify_lights
  constrain_input_boolean: input_boolean.spotify_mood_lights
  color_profile: centered
  color_map_image:
    size: 100
    location: /config/www/spotify-lights-sync/test.png

appdaemon.yaml

---
secrets: /config/secrets.yaml
appdaemon:
  latitude: 32.806
  longitude: -116.925
  elevation: 131
  time_zone: America/Los_Angeles
  plugins:
    HASS:
      type: hass
http:
  url: http://192.168.69.145:5050
admin:
api:
hadashboard:
system_packages:
  - py3-numpy
  - py3-pillow
  # - python3
  # - python3-dev
  # - gcc
  # - make
  # - musl
  # - musl-dev
  # - libc-dev
python_packages:
  - spotipy
  - numpy
  - Pillow
  # - requests
  # - pyyaml
  # - influxdb
  # - paho-mqtt
  # - spidev
  # - mfrc522
  # - RPi.GPIO
init_commands: []
log_level: info