Date: November 16th, 2021
If you see a "Redirect URI mismatch", the URI in Amelia and the URI in Google Developers Console are not the same.
Please go to Amelia Settings/Integrations/Google Calendar and make sure that the URI you see in there is your website's URL, ending with "wp-admin/admin.php?page=wpamelia-employees". For example, if your website is "yourwebsite.com", the redirect URI needs to be this:
Is your website in HTTP or HTTPS? Please note that Google doesn't allow HTTP at this time, so if it's HTTP, you'll need to install an SSL certificate and move your site to HTTPS before you can continue.
After verifying that, please go to Google Developers Console, and in "APIs & Services" go to "Credentials". Under "OAuth 2.0 Client IDs" click on the name of your app:
In there, check the "Authorized redirect URIs" on the bottom of the page. Make sure that the URL has to be the same as it is in Amelia/Settings/Integrations/Google Calendar.