During integration, this message appears after clicking on the Add button in the add-in installation window. The Antidote integration procedure is performed by Outlook, which looks for the add-in on a server.

To verify whether the problem originates from our add-in, we invite to try installing another add-in (Todoist, for example). Seeing the same message when trying to install that add-in would indicate that the problem lies with Outlook. In that case, we invite you to contact the Microsoft team.