You should first ensure that the bit rate (32-bit and 64-bit) of Mindjet 15 and MSOffice (Outlook) 2013 are this integration to work. You can find the bit rate under the File Tab and Help in both Mindjet and Outlook. If the bit rates don't match you can correct this by reinstalling MS Office or alternatively you can uninstall Mindjet 15 and then download the correct bit rate of Mindjet 15 version from these links (32-bit or the 64-bit).
If the bit rates do align then check to ensure your Mindjet outlook Outlook 2013:Go to file --> Options --> Addins --> dropdown menu: Disabled Items. If MindManager addin is listed, select it and click enable. Restart Outlook.
If you still encounter issues I would suggest running a repair from your control panel and see if that helps to resolve the issue. If this fails please contact our support team at firstname.lastname@example.org.