When attempting to use the Dynamics 365 App for Outlook, you see the following message:
"You are not part of this organization. Please contact your administrator.”
This error can occur if there is a security group associated with the Dynamics 365 instance and you are not a member of that security group.
Ask your Dynamics 365 administrator to add you to the security group which is associated with the Dynamics 365 environment you are trying to access.
If you are a Dynamics 365 administrator, navigate to the Power Platform Admin Center. Click on the name of the environment that the user is unable to access and then click the Edit button. If the Security Group field is populated, verify the user is a member of that group. If the security group is managed in Office 365, you can add the user to the group from the Users area or the Groups area within the Office 365 portal.