Teams Add New Members – You Are Not Authorised
Using Teams and trying to add External contacts as members of a team? Lets see what happens.
Open the menu to a team and click on Add members.
Lets try and add an external contact as a member by entering their email address and clicking Add.
We get an error message saying we couldn’t add member and you are not authorised.
If you add a user within the tenant it works fine, what’s going on?
The issue here is that only contacts who have an Office 365 tenant associated with their email address can be added as members of a team site. Basically the external contact must be using Office 365! Not even a Microsoft live account can be used, it must be an Office 365 account.
Hope this clarifies the issue for you! and it would be nice if Office eventually let us add non 365 accounts but that’s unlikely to happen any time soon if at all.