Can't Authenticate Google Calendar

Can't Authenticate Google Calendar

Inside the option Google on Marketplace, the whole organization can't authenticate their Google Calendar. After selecting "Authenticate Google Calendar" and selecting "Allow". (with the same email address that we have on Zoho CRM). It goes back to the same page, and the button "Authenticate Google Calendar" still appears, and we can't select, how to sync the calendar (two ways, one way, etc). We can't sync Google Calendar with CRM!

This happens with different browsers, on different computers and on different users. 

We really need help, this functionality stops the operations of sales that use the integration A LOT.

Thanks for your fast response.
Franco