In order to be able to add meetings to your FastMail Calendar you need to connect your FastMail account with Harmonizely via CalDAV protocol.
FastMail needs its own app password to access your information. If you use your normal password or your FastMail two-step verification password, connecting to Harmonizely won't work and you will see a password error.
1.First, navigate to your FastMail account and create a new app-specific password.
2. Make sure that your FastMail app-password can access CalDAV data (should be enabled by default).
3. Go to Calendar Integration in Harmonizely.
4. Click Connect button in CalDav Calendar section.
5. Fill in your server URL, email address and app password:
Calendar name: Your random calendar name, e.g. Zoho.
6. Click Connect Calendar. Harmonizely will connect your FastMail calendar.
7. That's it! Your FastMail calendar has now been added to Harmonizely and should synchronize with your FastMail account.