There are some hints on how to get rid of errors here: https://ankiweb.net/shared/info/924111087.
You are using in macOS and this add-on only test at windows system, and you can avoid this error message by diable the config of “restore_last_on_off”: from tools-Advanced MPV Player->restore_last_on_off or chage the config file from Add-ons dialog.
AwesomeTTS should work without this addon.