Axigen calendar not working in EmClient

Hi,
I’m having a problem setting up the calendar on EmClient and hope someone can help me out.

I went and configured a new CalDav in EmClient and the connection went trough but no events are getting in. So if I send a test meeting to my email address I can see the email coming, click Accept but it is not added to the calendar.
Also, I if try to add a meeting I will get a message that I do not have permission (Failed to upload item)

When I configured CalDav in EmClient I entered the client Web portal FQDN, like https://mail.domain.com, the same one clients use to access their email trough the browser.

Any idea will be welcomed.

Thanks,
Adrian