can;t get google calendar to work with appointments plus

I can't get google calendar to work with appointments plus. I deactivated it last night but want to try again as it seems to be what the client needs.

I got up to the point of entering client ID and key but get an error on the last step of verifying it

How do I get the plugin to show up on the site? Shortcodes? I didn't see a way but maybe because I can't get google calendar to sync up?