Follow steps below to add OTJ add-in:

  1. Open your Outlook account in any browser.
  2. Select any email.
  3. Click on the three Dots.
  4. Click "Get Add-ins".
  5. Select "My Add-ins" tab.
  6. Click on Add a custom add-in 
  7. Select add from URl and past this

  8. Click Ok then install.