Do you have more information about the issue? Was it along the lines of:
Need admin approval
eM Client
needs permission to access resources in your organisation that only an admin can grant. Please ask an admin to grant permission to this app before you can use it.
If so, I experienced that too. It arose because of a change with the handling of Outlook security (our IT people blamed Microsoft for making a change they were not expecting) and it took them a little bit of time to work out how to solve it. After they worked out the details of the issue and granted access, I was in.