Has anyone run into this weird problem?

My email server is Office 365. When I try to configure Zoho CRM to use this server, a Microsoft popup window opens requesting user and password. After entering that, I get a message in the Microsoft window saying that the admin must grant permissions to access organization resources.

I have no idea what permissions are those (the Office 365 admin is immensely complex), and the weird thing is that my other users have connected CRM to the same 365 Exchange server with no problem. However, I don't find any difference in configuration.

Zoho say it's not on their side and they don't know.

Microsoft takes ages to respond and it's incredibly confusing.

Has anyone seen and solved this problem before? I'm going crazy here.

Thanks.