Why does my Outlook take so long to sync with Zoho Calendar for the first time?

Why does my Outlook take so long to sync with Zoho Calendar for the first time?

This behavior is quite normal for the first time you sync with your Outlook Calendar. It happens due to the large volume of data, and it takes a lot of time to transfer the data. We recommend you to wait for the process to complete.

Refer here for more details on Zoho calendar Outlook plug in.