When users open the Chili Piper extension and see this error message "users have not shared permissions with you" there are 2 reasons for this occurs.
1. The user has actually not made their calendar sharing settings public.
How do you fix this?
1. Office 365 enables you to make calendars available to “external users,” those who need to see free/busy time but don’t have user accounts for your Office 365 environment. To enable calendar sharing for Office 365 please follow these instructions here.
Google enables the exact same functionality to make your calendar available to external users. To enable calendar sharing for Google Calendar please follow these instructions here.
2. The user's calendar connection has been lost in Chili Piper.
In this case, you will need to log in here and click "reconnect" - https://apps.chilipiper.com/meetings/personal-settings/integrations
Once you reconnect that should do the trick.