The OU that the user is in is enabled and selected within the "Select OU's windows".
This error occurs for random users. Most users can log in successfully however a small amount experience the error "Permission Denied. Kindly contact your Administrator". They are all in the same OU in Active Directory.
Please update the credential provided under the "Domain Settings" (when the software is running as an application) page and then try to login. Follow the steps provided below to update the username/password.
* Click “Domain Settings” link on the top right-hand side corner.
* Click “Edit Domain Details” icon under “Actions” column.
Note: The “Domain Username” and “Domain Password” must be of the user belonging to “Domain Admins” or "Enterprise Admins" group. When running as service, please add service account on the "LogOn" tab under the service properties.
Further, please follow the steps to remove the users from restricted users list (if any).